Co-morbid ADHD...meds advice please

My almost 7 y.o. DD  is on Lamictal and Keppra (and B6!) for seizure control.  One of her biggest "tells" for seizure activity without a physical indicator is an increase in her impulsivity.

Because of this, we want to switch her ADHD med this summer from a stimulant (Focalin XR) to a non-stimulant.  Have any of you had to do this?  What advice do you have?