ok, so what if there was a sucker punch 2? well, this is what i'd do with it...
Following her lobotomy, Baby Doll keeps having strange action-sequence dreams. After a while, she reaches the Wise Man who tells her that in the afterlife, Blondie has been condemned to 5 years of being a prisoner for betraying the others, Amber faded quietly into oblivion, never to be heard from or seen again, and Rocket is trying to find a way to communicate with Sweet Pea. Baby Doll is shocked to realise she knows who they all are and what he's talking about.
As Baby Doll wakes up, Blue tries to seduce her, telling her she wants it, but she refuses, punches him, and tells him that she remembers everything before leaving. Blue confronts the guy who did the lobotomy, and he confirms that he did complete it. Blue, angered, sends men out to look for Baby Doll who has managed to slip out of the centre as, technically, she no longer exists.
After a while, Baby Doll his her head and whilst unconscious, is able to contact Sweet Pea. She tells her that Rocket is looking for her and she needs to be prepared.
Baby Doll wakes up, being carried back to the centre, though she resists. Blue holds her still and tells her that her job is not to get herself or the other girls killed, and rapes her. Afterwards, he tells men to search for "the one that got away."
Baby Doll fights Blue, but he slaps her and tells her that she can't beat him, no matter what she does. He reminds her that three of her friends are dead and one is about to be dead. He tells her there's no point fighting it, and she obeys.
He then seduces her and they end up having sex, him having complete control over her.
She wakes up early and climbs out the window, but she falls presumably to her death.
The next thing we see is Sweet Pea being dragged into the centre, limp, and into Blue's room. Blue tells Sweet Pea that the others are all dead, even her "little blonde saviour," and tells her that she'll be the last.
Rocket suddenly appears and says, "Goodbye, Sweet Pea. This isn't the end yet."
Finally, we see Baby Doll looking up from the grass, a determined look on her face.
TA-DA!! Yeah, its not very good, but its more or less what i'd do...