Heh on a game screwing around I hit that limit before, bought some more rooms and it fixed itself after a few rounds of my rooms dropping into negatives. When playing normally though I usually limit myself to adding 10 rooms per brothel. If you have a girl whore during one shift then work a random job the other you can fill all job slots even in your first brothel doing this; but will have a hard time getting customer happiness above medium. You could also not have a casino/bar or both in your first brothel and make your brothels better as you prgress. Though, if you're hitting that number and wanting it adjusted I assume you aren't trying to find ways to draw the game out for yourself in it's current unfinished state.
I look forward to seeing it's finished version, or at the least, the next version. Even if it's never finished though, I can find ways to draw it out myself; as long as I can continue to add my own girls and less importantly items, I'm happy with it.