Lamictal really just works for the depressive end of Bipolar it has little to no effect on hypo/mania shifts.

It’s likely your Abilify is what’s keeping the mania at bay. Meds seldom stay the same dose for long periods of time.

Bipolar cycles and usually at some point meds need increased or a new med added etc.

It’s likely your Abilify dose will increase to keep you at baseline.