It's not necessarily a "oh, I changed my mind about this girl...let me change my vote."

What if a NM doesn't fulfill financial obligations? Doesn't pass her NM test (generally speaking, since a lot of sororities have them)? She's a rotten NM who causes harm or damage to the chapter? Or, in the OP's case, decides to leave school prior to initiation?

I can see a pledgeship carried over to the next semester for the first two, but if she leaves school and intends (at that time) not to come back?