First and foremost, I recommend that you do a little detective work and be sure that she is washing and rinsing properly when she showers. I went through the same thing with my boys and found out that they were rushing through their showers, not soaping and scrubbing well, and sometimes they'd not shampoo their hair! Once I got them back on track, the BO problem lessened considerably.
At about age 10 I noticed that T would get stinky feet and some BO. So I bought him foot powder, deodorant and instructed him on how to use it after showers. I also talked to him about changing socks and laundering his clothes. I don't know about your kids, but mine will try to wear their favorite shirt over and over. Be sure your daughter's leo is being washed and dried well.
http://www.amazon.com/Keep-It-Kind-Fresh-Deodorant/dp/B00...