Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
Levetiracetam has been associated with pharyngitis, rhinitis, and cough in 4-14% of patients. It can lower blood counts in ~2% and cause flu-like symptoms in ~5%.
Patients with epilepsy may be refractory to medicines. These patients should be evaluated for possible epilepsy surgery, especially if they continue to have seizures despite trialing 2-3 medications.
People with epilepsy may also seize because of missed doses of medication, infection, or inadequate medication dosage.
I would suggest that your niece be evaluated by an epileptologist associated with a surgical epilepsy group.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.