If reincarnation is real, and the world ends, where would we reincarnate to?

Well you may or may not look the same in your next lifetime. May not be the same race or, some believe, the same gender. The dna is simply the coding for the physical body. Reincarnation is adhered to by many religions. Even ancient Christianity had reincarnation beliefs. At the very least waiting for Jesus to return would be similar.
https://en.wikipedia.org/wiki/Reincarnation

Or even the same species...

In my next life I'm coming back as either a sea otter or a jaguar... still haven't made up my mind yet.

let said I want to back in time, some reasons, I want be hilter. because i want understand hilter better than history books we said about him. i set my time machine back to ww2, few weeks or a week before hilter competed suicide.

so i set my time machine to that location and the date. i went back in time, i miss the window being hilter. i was in nasi's concertation camp, as a prisoner, because i was a jewish.

the question if you can jump back in time to being someone, you want be. would your dna allow you to it?

has anyone consider with time machine's ideas, that your own dna can alter the reality of timeline, not your actions during your time back in time.

I'm thinking big fat house cat that belongs to a crazy cat lady.

I assume you heard about the 400 pounds mouse in the news recently. the mouse said one thing really loudly: " HERE, KITTY, KITTY !! "

Correct, they aren't ghosts anymore after they reincarnate