How do you heal Compa and IF in Hyperdimension (PS3?)?

I just got the first game for PS3 and I don't know how to heal IF and Compa. At the beginning of each random battle that we have, Compa and IF both have 1 HP and they die within the first few attacks of the enemy. Then, it leaves Neptune all by herself. Neptune eventually dies every time and the only choices are to try again or go back to the main menu. But the HP of Compa and IF are always 1 HP, so it's a neverending cylcle of defeat and restarting, pretty much. How do I get Compa and IF to stop dying and heal themselves?

I max out their chances on the items that each have for healing, but they never use the item, most likely because it's a low percentage. I only can max it up to 55%.

The healing skills only have a certain percentage chance to be used under certain conditions, like when they drop below 50% HP. There's no way to heal during battle other than through those skills.

The only other thing you can do is leave the dungeon which will bring everyone to full health.

Honestly, I'd probably just skip the original games and play Re;birth 1 because it uses an updated system that fixes a lot of the original game's problems.