Is an EEG preferred when adjusting Vimpat levels?

I'm a family member helping with an epileptic and about a year and 1/2 ago, an EEG and related studies were done over 5 days to determine proper medication levels for her.  And the resulting medication regimen has been much more effective at controlling the epilepsy than what she had before.  She still has seizures at times, however, and the medical person at the neurology clinic we work with decided to recommend another 5 day EEG.  I was wondering if this would likely result in a better outcome than a Vimpat bump up to the next 'notch', or is it a step too far?   As in, would a Vimpat adjustment be a better thing to try first, and then more expansive procedures?    Or are there side effects to consider?

Thanks everyone!