Let me know which version of the theme you want to use and I'll create you an auto-looping small-size OGG you can use and/or include with the next version etc etc
EDIT: Ah crap I game overed at the current final boss (I think it is. Abyssal Warbeast). Ah crap I didn't make a secondary save.
Even more aw crap, there's no place to even fully recharge my party FFFFFF
If your party's hp/mp numbers aren't completely screwed, you could try running around hoping for level ups for the more mp-intensive characters like Hime and Rou (I personally ran circles in the boss room for Rou to get a level up to max her out before fighting the boss). I found that Sana, Purvis, Alstro, and Sapz aren't as mp-dependent due to their cheap skill costs, so it's not as important for them to be maxed out on mp.
Of course, if everyone's running on empty, it might be hard fighting the battles to get those level ups.
Also, backup saving should be second-nature,
especially when you encounter a teleporter that specifically warns that you can't return until your business in the dungeon is done.