So let's imagine that Napoleon dies in Russia. By accident, assassination, or maybe he just drops dead. A lot is up in the air in Europe and no doubt Britain will still have a lot of focus there.
But with less financial and military spending on the continent, what does Britain do during it's war with the US? Do they still half ass it? Or do they throw everything they've got at the fledgling nation? I don't suppose they can reconquer the US, but can they prevent it from dominating North America? Or will the Americans just come back stronger?