For the sake of argument let's say the Brits pull the rabbit out and curb stomp the Americans, are they prepared for the long occupation necessary to prevent the next round? After all I can see the Brits continuing the same arrogant attitudes that triggered the war to begin with only now the US will be building up for the next round.
While Britain could interfere for a while sooner or later the loss of treasure in keeping the US from growing again will become unsustainable.
New England would likely become scapegoats for their actions and there would be less resistance to expanding both the Navy and the Army plus supporting infrastructure.
I could see a series of wars constantly breaking out between the US and Great Britian much like the constant series of conflicts between Great Britian and France in the 1700's.
I can see several things wrong with this:
1 - Britain wouldn't occupy the USA, nor even parts. There would be no cause for it. Britain had given up the lost colonies in the Treaty of Paris and it had surrendered its claim thereupon also. It had no plans to annex the USA or parts of it. Even if it was given a golden opportunity to do so, it would be strategically unsound to do so. The USA had already proven its fighting ability in the ARW and even if the UK beat it this time around, even comprehensively, then the British still wouldn't want to risk having to do it again by doing the 19th century equivalent of a Versailles peace. Britain could do better than fighting repeated wars to ensure its dominance - it wasn't Bismarck Germany and didn't want to be. The UK was much more interested in accepting what was over and making the best of it. At the worst, the peace deal would require recognition of New England's independence, and even that is only if the New Englanders actually made the first move. If NE didn't make a bid for secession then the British wouldn't even push that, they'd likely just have contested borders settled more in their favour, insist on some deal for proper treatment of the American Indians on the US side of the border, and then negotiate on a settlement on the causes of the war. The UK had no interest in breaking the American state, it was far more economically sound to befriend it so that it could profit from the American reliance on British trade.
2 - The British "arrogant attitudes" are only arrogant from the American point of view, and they don't translate into sneering and looking down upon the Americans. As stated before, the British had really quite humbly accepted the loss of the colonies with good grace. Support in the UK for the Americans during the ARW was widespread and reannexation would be universally unpopular. The politicians didn't want to revile the USA, there was no basis for it. The only causes for the war from the British side were attempts to block American trade with France, the British press gang, and the "supposed" British interference with the Indian tribes. Of these, the disruption of trade was vital to beating Napoleon, the press gang was viewed as at best a military necessity and at worst completely unavoidable, since crew members took recruiting into their own hands no matter what the Government said about it. The Indian issue is still unproven and at worst not something to go to war over. I'd contest that the American's desire to land-grab all of the Americas was the real motivation behind the war and far more illegal and immoral than any of the British problems, not to mention far more "arrogant". The British never made any pretense to being destined to rule parts of the world, even after over a century of supremacy. Conversely, even as a fledgling nation it took barely a couple of decades for the American state to proclaim itself rightful owner of the American continent regardless of the feelings of the legitimate governments of the time.
3 - I fail to see how the British could interfere in American affairs. It lacks strength and intent to annex or assume control, and the American government seems determined already to follow its own course, and not to follow the crowd. It makes no sense, the idea of the UK attempting to pull the strings on American affairs.
4 - I would challenge your assertion that America would see numerous conflicts between the UK and USA. I stress one last time, Britain did not want to go to war with the USA. The UK had no interest in gaining anything from a successful war with the USA. It just wanted to forge trade links and rule Canada in peace. If there is constant warfare in the Americas it is my firm opinion that it would simply be due to the USA refusing to set aside the ideal of Canadian annexation, and nothing else. That said, this point is opinion only, so I can't claim to know better.
Actual force levels involved at Waterloo and the entire 1815 campaign:
https://www.alternatehistory.com/discussion/showthread.php?t=8673&highlight=Blucher
British overall manpower, far less than they could have summoned: http://www.napoleon-series.org/military/organization/c_casualties.html
Above force level does not include Canadians or allied Native American tribes.
Incidentally, Grim, I think that counts militia numbers; that, or all the regiments that were necessarily stationed in India. The Indian troops couldn't be moved except to be rotated, due to safety concerns. The militia by law was never to leave the British Isles; it was a defensive force only.