You dont release them when you do that upgrade, they become your prisoner in the cells. The cells is where most of the costumes will be unlocked. As far as I know there is no way around this tho.I have the three starting heroines in my cells and have them "maxed out". How can i release them without resetting them? I haven't been able to see any of their costumes in the meta-bordello and was really looking forward to it.