Do not bother, ivan.
This is all on you. As a responsible dev and server manager, the duty to back up all your stuff falls to you. It’s one of the core rules of computer usage, because if there’s a way for your data to disappear, it’s going to.
Bar is my name and to go bar is my aim...
Sometimes I'll go "Bad bar",
But in the end its always bar, ahem beer, ahem bar! beer bar!
I would say, it's up to you.
If you want to take it up, I'd say start back from 0, but those who payed for the game, will be ripped off. If instead, you give them their upgraded items, the game will be unbalanced since other people started back from 0.
So at this point, no clue.