Have you been giving her any additional supplements, particularly mineral supplements? You may want to try a multivitamin/mineral supplement in liquid form for her in case she doesn't have enough of the right enzymes to breakdown a tablet or capsule. Be sure to have her checked for anemia as low iron is quite common in children in general, but especially in celiac children, and low iron can greatly affect growth. Also, she may need probiotics, and plant enzymes to help rebuild her intestinal tract and breakdown foods in the meantime.
One thing I have found is that the children of ill parents often have a more pronounced version of the illness, earlier. So her damage may be further along her small intestine and may be affecting her absorption more. Also, children grow in spurts. She may actually be between spurts right now, but if you are actively working to rebuild her system, she may have a pretty big spurt next-go-round.