Hospitals can heal you. For a fee of course.
It will cost 1c per 1000 units of any Stat you want to heal for people up to 100,000 Power Level. It is 1c per 1500 units up to 500,000 PL, and 1c per 2000 units up to 1,000,000 PL. People above a PL of 1,000,000 are beyond the help of hospitals and must find other means to heal themselves.
There is a Hospital at every location and it takes one day to heal any amount of your Stats.