Does he have seizures? And does he say why he doesn't want to take the Keppra?
You might need to discuss this with his doctor, and see if there are other alternatives. Keppra can have some pretty significant side effects, and there are other seizure medications that might be substituted for it. My son took it for a while, but had to be changed to another medication after about 9 months. Some of the more worrisome side effects can include: anxiety - agitation - aggression - depression - headaches - mood changes.