I would keep her before some others. What are the adjusted weaning weights, assuming you sell your calves at weaning, for all of the cows in th herd? How well do the different cows calves show muscle? Any of them calve outside of a 45 day period? What are the individula cows calving intervals?
I'm assuming you have laready gotten rid of the obvious poor performers, problem breeders, anything that has had to be treated for any illness, those that are way too large for your resources (in normal years) or are hard keepers.
Now s when the hair gets short, but it's hard to narrow down to who will stay. Looking at them as which ones will stay is an easier way of selecting those that will leave rather then looking for those that will go. Not sure of that made sense or not, hope you get the idea.