A hero who dies or fails and wakes up earlier in their own life with their memories, then uses what they know to do it better the second time. Close to a time loop, except it usually happens once.
Aethon describes RE: Birth (ebook and audiobook October 20, 2026) as "A LitRPG Regressor series that gives a dying old mage the chance to go back and prevent the end of the world."