Characters like Rena can earn 100 SP by gaining the Sense of Taste talent. If she doesn't have it at the start, buy dairy products in Mars and have her cook until she learns it.
To access this post-game dungeon, reach the final save point before the boss Gabriel in Fienal (the save icon will turn blue). Return to Fun City and speak to the old man in the northern part of the arena to "recover your memories".
Whether you use a Caetuna code device to max your Fol or simply exploit the Reel-to-Reel duplication glitch in Linga, Star Ocean: Second Evolution offers a surprising amount of flexibility for players who want to skip the grind. By using the methods above—from affection exploits to item duplication—you can finally see the 99 endings, defeat the Angel of Death, and master the Pangalactic Federation without spending 200 hours in the Cave of Trials.