In that case it's up to her if she accepts that, it's unusual for an actor to choose to stay as a guest star (it'd be her choice unless she's desparate for work, which I doubt) but it happens when they want more freedom (Chris Noth in The Good Wife).
Not sure why she'd be averse to another year of steady work. It's not like she's any kind of star. She's done some indie movies, some TV guest spots, and an MTV show that no one watched and was quickly canceled.
Wait, wait, wait... What? Budget cut and ratings falling? WTF this season is miles better than the previous one.
Yeah, the ratings were better last season and this season got a budget cut despite that. Can't imagine next season won't as well.