These are my 2 suggestions for the energy bar:
1. It doesn’t have to fill up by 1 every 3 minutes (? i think). You could have the entire bar filled up each day. this would solve the problem of being away and the bar not recharging. (which i still have)
2. It doesn’t have to fill up completely every time you levelup. This makes levelling too easy. i’d suggest you give the player some energy back, but only some, not 100%