If you know what you're doing you can always make use of stuff like CheatEngine, Save Editor or the in-game console. I did try it with Save Editor and gave myself 1000000 levels but it just became boring.
You go in GrowthRPG/Saved/SaveGame, get the save file that you intend modify, and then drag-n-drop it on the Save Editor page, then it's just a job of actually figuring out which of the 43 PAGES of variables is the one you actually wan to change without breaking the rest of the game
which lines on what pages would I need to modify and how if I just want to have the xp? Need to ask cause the lines look all identical to me and I suck at programming...