First of all raise the issue with your Endo, see what he/she thinks about the whole thing.  I personally am reluctant to increase meds unless for illness.  I think that giving extra meds to prevent something occurring may result in constant increase in meds to prevent one thing or another, and therefore affect levels, growth etc.  I have raised this issue with our endo (our daughter is only 3) and he suggested that if she were to get fatigued playing sport when she gets a bit older, giving a sports drink (Gatorade or something similar) may be necessary.

Good luck