unfortunately due to the way the thing the game is made on works making a new version of it makes any saves from a previous version unusable (it'd still be pretty unwise to use older saves even if it was possible cause chances are they would break anyways)
fortunately your achievements are maintained if you beat the game, and achievements give you permanent buffs, if you got a handfull of achievements it becomes waaaaaay easier to beat the game over and over, once you get many you are basically a killing machine lol