She's super-over at the moment and they're trying to capitalize by giving her as much camera time as possible, but yeah, this kind of thing happens a lot and it results in audience burnout. It's too bad because she's legitimately talented and seems to love her role.
On another note, cute as she may be, she looks too much like a little girl for my tastes. But since they cater to a young audience, it does make sense that they'd push her.
It'll work for awhile, I'm sure. But "permanent" definitely does not mean "permanent".