My suggestion, since the game is still active, is to have an IC event that resets things. If it's magical in variety had some sort of memory wipe spell gone wrong. Maybe these events did happen but no one remembers so it's a clean slate. Or a time jump. Someone does something that literally resets the last few months/years/however long you want and you get a redo.
I haven't even restarted a game while it was still running so I don't know how well that will work out, but I thought having a clear IC reason the game is rebooting might make it easier for current players.