S.B.
K.,
I understand how horrified you must feel about the behavior that your daughter is exhibiting. My son is now 4, and when he was 2 he also bit another child. It happened at daycare. First, my son, Conner, went to a time out while the daycare provider tended to the other boy's wound. Teeth marks were definitely there, but the skin was not broken. However, the boy was tramatized and screeming. For my son, that was all it took for him to understand that he had done something very bad. After a couple of minutes, he was able to come out of time-out and the daycare person discussed the event with Conner and the other child. Conner helped put an ice-pack on the boy's shoulder where Conner had bit him. Luckily, that was the last time he bit at daycare, but he did get a little too rough with me and my husband on two other occassions afterward. On each occurence, Conner had a time-out, we talked about what happened, he saw the "boo-boo" that he caused and we told him how much it hurt. He kissed it to make it all better. That was the end.
I would keep doing the quick reminders that you are already doing in the morning at drop off time. If it happens again, then make sure that she understands that she has REALLY, SERIOUSLY hurt the other person. We are not joking around; it really did hurt. She should not only say, "I'm sorry" but also do something that shows how sorry she is. She can help with ice, kiss it, or whatever.
Remember, too, Mom, that this behavior is not a reflection of your parenting skills. Don't take it personally. It is just your daughter's way of testing her own strength... and independence.
:-)