Does she have to be saved by first aid at the scene or will reasonably
prompt surgery suffice?  If first aid at the scene is important, then you'll
have to make it a stab wound to the periphery, such as the upper arm.  Punch
a big hole in the brachial artery, for example, and someone at the scene had
better do something quick if she's going to survive.

http://iris3.med.tufts.edu/dentgross/fig4.jpg

There's little or nothing first aid can do for injuries to major organs, so
if you need her to be stabbed in the torso she's just going to have to be
very lucky.  If getting to a hospital fairly promptly and having it repaired
there is okay, then you can have her stabbed almost anywhere, even a lung or
other major organ.  She just has to be one of those incredibly lucky people
where the knife misses all the major vessels.  To make that scenario a
little more plausible, I would put the knife in her flank.  Along the waist
at her side where it could plausibly miss the liver, intestines, etc, or in
the rib cage at the side, where it might be deflected by rib and miss her
lungs.

Have her bend over during the struggle and the knife enters the throat. Lots
of gushing a wheezing for effect, but would not be fatal.