Wouldn't Anakin have noticed if she survived and gone after her? That's pretty lame... I mean she fell off a cliff! Why don't we assume that characters like Palpatine, Mace Windu or Darth Maul survived, since they were offed in similar fashion (falling). Why isn't it "unclear" that these characters are dead?
Oh well, it just seems like an all-too-convenient cop-out way to keep the character alive just in case they want to have future stories about her and/or to fuel fanboy fantasies (a la Boba Fett).
But it's a comic book tradition to implausibly bring dead characters back to life, so oh well.
They should bring back Chewie next!
Edit: From the entry it sounds like she was killed and resurrection numerous times, perhaps in imitation of various legendary accounts of "immortal" villians in history and literature. They might as well just say she was cloned or something, at least that would make more sense.