For lice I would continue with the permethrin dust every 5-7 days,
around vent and neck, under wings and belly.
I've read about coating lice eggs clusters with coconut oil to suffocate them and keep them from hatching.
Are you positive they have lice and not mites?
Roost mites are much harder to get rid of as they do live in the structure much more than poultry mites or lice(both of which mostly stay on the birds bodies).
My Bug Check Blurb:
Google images of lice/mites and their eggs before the inspection so...