Poland was actually partially brought back in OTL. Tsar Alexander fought for the establishment of a semi independent Polish state, and was supported by people like Czartoryski. He faced a lot of opposition from the other great powers, however. Prussia was still unsure whether they would be compensated in the west, so they were unlikely to easily give up their Polish land. Likewise, Austria had little reason to want to give up her populous Polish provinces, especially given how much she had lost in the Napoleonic wars.
So you have a couple of options for the establishment of an truly independent Poland:
1. Alexander is more successful in the war against Napoleon, and has fewer people push back against his plans. Maybe he manages to become the great general he always wanted to be and “commands” an army that defeats Napoleon personally.
2. Alexander is made king of Congress Poland like OTL, but after his death the Kingdom splits off and gets its own Romanov branch for some reason.
3. My personal favorite but pretty unlikely unless we go pretty far back. If we change the situation of occupied territories a little more we can achieve a scenario where perhaps France (or a new “Rhineland” state) gets the western land that OTL went to Prussia. Prussia, in turn, demands to be compensated with the entirety of Saxony. Like OTL, there is a large public outcry about dismantling King Frederick Augustus’ domain but the Prussians win the day. Then Frederick is offered the crown of Poland with “Congress Poland esque” borders. He would have the most legitimate claim to a Polish Kingship. I don’t think this scenario is very plausible and it’s more likely to lead to war but I suppose it could happen.
Now to call in the real experts
@alexmilman @Jan Olbracht