It sounds to me like you actually have 2 concerns: (1) whether or not your child is actually learning anything at all; (2) whether she might get kicked out of the program in the future because her scores aren't keeping up.
For #2, I would definitely be supplementing with resources at home. But not IXL. IXL is great for practicing skills you already know, but not good at teaching them. KhanAcademy has some great videos and that's where DD has probably learned the most. She also likes Dreambox.com which is more "fun". You could also simply buy a curriculum for 4th grade math and do it at home. That's what we did last year--I bought a textbook off eBay (same curriculum our public school uses) and we started the 3rd grade textbook last April and finished it in August.
For #1, I think you've gotten some suggestions above so hopefully those will help. I had no luck whatsoever battling the powers that be in our old district. And I can't take much credit for accommodations in our new district; they were simply much more helpful from day 1.
