What role do anti-seizure medication levels, such as levetiracetam, serve in seizure-free patients?  

In patients with epilepsy who are being treated with antiseizure medication, the change in doses has to be driven by clinical data, mainly by seizure recurrence and/or adverse events. If a patient has been seizure-free and is not having adverse events, there is no need to check for blood levels, as ...

I would add that at certain times it may be required from a legal standpoint to maintain driving privileges. This falls under the more general category of "verifying compliance", which is admittedly optional if the patient is generally trustworthy.

None.

I prefer doing it yearly. Over time, there can be weight changes, and different generic brands may have varying absorption rates. With pregnancy, I do it monthly and most end up on 30 to 100% more medication towards the end.

Checking compliance for Keppra is important. Otherwise, it is generally not used unless it results in a change in management. Dosing changes are primarily driven by the clinical control of seizures and the side effect profile.