To improve security, we will soon start forcing password resets for any account that uses a weak password on the next login. If you have a weak password or a defunct email, please update it now to prevent future disruption.
You can edit the save files. There in the subfolder:
<game install folder>\TheKnightGirlAndDungeons_Data\Saves
and they are editable JSON.
Load a "Slot - x.json" in an editor like Vscode, reformat it to make it human readable (<shift><alt><f>) and then scroll to almost the end of the file. There is a section starting with "PlayerStatusData". There you can cheat values like "money" and "maxHealth".