Wow. Could you not kill her at the moment because you're unsure and maybe send her on a trip so she's out of the picture until you decide completely?
Does she have qualifications to go and do research on Antarctica where they can only get down there at certain times of the year to keep her gone for awhile?
I'm being a little facetious and overboard with location just to give you an idea of what I mean. Please don't do the old soap opera... they're in a coma thing though.
Then if you really decide you want to kill her off and use her death as a plot point have her killed on the way back....
This is all off the top of my head here.
Anyone? Any other ideas?