I was diagnosed a couple of years ago but I seem to remember it took me a while to get my energy levels back. There was a big change in the first week or so after I was diagnosed, I felt so much better than I had for quite a while. However as things began to settle down I was back to being pretty tired for a while longer, I was also VERY hungry for a few weeks. It seemed reasonable to me that after having lost quite a bit of weight before diagnosis that my body was going to take a while to adjust.
That said if it doesn't seem to be improving or you are particularly worried it would be worth mentioning it to your daughters Doctor or DSN as it could be a sign that there is more going on.