As it stands now I could avoid losing money by copying my save, going into a dungeon fully decked out, and if I fail copy my save back. Or with enough time and effort I could use cheatengine and start messing around with variables to give me an advantage.
If you are concerned about it being used to cheat easily, do what other games with similar concerns do: saving immediately saves and exits the game. When you load the save, it starts the game and deletes the save.
People who want to cheat will. If it's a matter of achievements or high scores then maybe give an option to only allow online saves, no local saves, and mid dungeon saving. And exit when saving. Then people can't mess around with the save.
Or if you want to get REALLY interesting...save the parts of the map that are exposed and regenerate the rest of the dungeon randomly so the hidden parts are different each time? Don't know if that's possible with the way dungeons are generated, but it would stop the kind of cheating you are concerned about.
I don't want to cheat, I just want a chance to finish a dungeon!