S.E.
I agree with all the postings to an extent.
However, I say give her a little pinch back. Not enough to hurt her, but just to let her know - it's unpleasant. The other big thing is to take your attention away from her. She will understand that.
My son went through a biting stage (at about 2 1/2 years old)and I did all the "right" responses - redirecting, time out, etc. Finally one day I had had enough and did what my granny told me to do months ago - he bit me on the arm, and I simply took his arm and gave it a little gentle bite. Not enough enough to make a mark. Well, he didn't like that one bit and pitched a fit, but he never bit me or anyone else every again. Also, my son never started biting or anything else until he started preschool and was around kids whose parents who thought their "non-violent" approach would result in desired behaviors. They were some bad kids. You have to find a balance between new school and old school. As my granny said, some behaviors are what you call "non-negotiable". Meaning, they warrant immediate action.
As far as long term effects of negative response...blah blah blah. Yes, you can redirect and role model all you want, but sometimes action is what you need to get a child's attention. Why don't you ask all the teachers you know about how differently behaved children are now than they were even just 10 years ago. They will tell you kids are much more poorly behaved and socially maladjusted. Because we have shied away from taking a firm stance on behaviors that are not acceptable.