How about certain skills give bonus MP or a skill that gives bonus MP?
If you don't want a new skill you can use concentration as a way to get back MP that have been used since the PC enters a meditate state. You need to mediate for 1 hour but depending on the DC on the DC determines how many MP you get back. For example a DC 15 will get you 5mp, a DC 20 will get you 10 MP, a DC 25 will get you 15, etc...
If you want a new skill you can call it Reverie. Each rank in it gives you the mage class level in MP back per hour if you make a Skill Check DC 15. For each 5 over you make the check you get a +1 MP back. This skill has a synergy with Concentration +1 for very 5 points in Concentration.
Now this was from the top of my head and will most likely have to be tweaked a bit but hopefully you get the picture.
-NetNomad
If you don't want a new skill you can use concentration as a way to get back MP that have been used since the PC enters a meditate state. You need to mediate for 1 hour but depending on the DC on the DC determines how many MP you get back. For example a DC 15 will get you 5mp, a DC 20 will get you 10 MP, a DC 25 will get you 15, etc...
If you want a new skill you can call it Reverie. Each rank in it gives you the mage class level in MP back per hour if you make a Skill Check DC 15. For each 5 over you make the check you get a +1 MP back. This skill has a synergy with Concentration +1 for very 5 points in Concentration.
Now this was from the top of my head and will most likely have to be tweaked a bit but hopefully you get the picture.
-NetNomad