Is there any way to get back to town from the dungeon without getting a game over? I know you can get to town from the escape menu, but you still lose your P and items which kind of defeats the purpose of having a "Please get me back to town before I lose all my loot" button.
As you progress, you can get upgrades that let you keep some of your items/money on a loss (with the final upgrade of both resulting in no loss at all), as well as gaining interest on your banked money after every successful mission, regardless of difficulty. Some upgrades and upgrade tiers only become available after certain ranks, so if you are struggling, keep replaying the normal rank missions and upgrading where you can.