No, don't fight back or say anything mean! The best is to follow up with another teasing line.
You can often simply rephrase exactly what you said in the first email and say:
Another way is to say something like:
"You don't like answering questions? Anything else you can't stand?"
Play dumb, or greatly exagerate something she said or pretending she said something when she did not.
She will usually try to defend herself, which leads to very interesting interactions ;)