Have you ever reintroduced yourself to someone because you're no longer the version of you that they know? Did they stay for long or did they leave?

Do you mean in a literal sense? I think that for me, reintroducing myself would feel unnecessary because they will quickly notice that I've changed. Maybe I would just tell them a bit about the things I do differently now, or views that I've changed like: "Do you remember when I said I'd never want to quit smoking? That was so silly." Idk, something like that lol.