Is there any way to get down into the mine without having to climb up as soon as you get back? Any save after a few floors? Or an item that goes back to farm. If you do not have some easy way to get gold ore?
The only short way/save up is the red stairs at level 20. When you climb up it you end up at the mines entrance. The doorway that opens up after your climb, thereafter acts as a shortcut to lvl20. Gold can be found from lvl16 and deeper.
You can also find an Exit Mouse who will help lead you out of the caves, but will disappear the moment you leave (it's kinda cute). And if you defeat the boss on level 40, you'll find a ladder that can take you up to the top, too.