Hey Mandy -
I take singulair regularly, montelukast, 5 mg a day right before bed. I love it, it helps me not only with my severe allergic asthma, but also my allergies. I take allegra 150 and also Symbicort.
If she has allergies, it's not a bad idea to keep her on the singulair, in my opinion. There have been no reported long-term effects of montelukast. Some people report side effects in conjunction with singulair, but all can be attributed to other conditions those reporting them have.
That's just my two cents, but I think that's a decision you and your daughter's doctor should carefully consider.