Another thought would be to get rid of the cap on RP per level and Rebirth award MP. My Rockster rebirth upgrades are in the billions now so it would take almost 10 days of 24/7 playing to upgrade all three one time each.
I have no idea how much time or effort it takes to alter something in a game. I am purely a gamer. My programming knowledge began and ended in 1982 on the Spectrum 48k with:
10 PRINT "I AM A NOOB" 20 GOTO 10 RUN