If you want my opinion . . .
I went through the XR 200 thing. They are good bikes for the hills, NOT for mx tracks. That is just not their intended purpose. I wish I had started on a mx bike of some type b/c I would be a better rider for it now. If she is a competitive person--and if she's getting air on a mx track, she is--she might enjoy a two-stroke more. Now this subject has been beaten to death but like I said, these are just my opinions. She WILL outgrow the XR. There isn't much you can do with them. How big is she? A KX 100 or a YZ/CR/RM/KX/KTM etc 125 might be a better ride. Yes, they are more intimidating. Yes, they can get out of hand more easily. But you won't spend $$ you won't get back trying to polish a turd (no offense to XR riders) and she won't get tired of it so fast. If she's bottoming out the suspension after 3 months, and is tall enough, I'd recommend a 125. She will be a better rider for it in the end. I have SO MANY bad habits from my year on an XR. You just don't learn the throttle control, clutch usage, brake techniques, and good riding position on an XR because they are so forgiving and you don't have to. I still crash way more than I should because I grab the front brakes too hard.
So there you go, that's my opinion on the subject as a former XR rider. Email or PM me if you have any more questions. Oh yeah, and get her signed on and she can hang out in the women's forum.