Other prescription medications that have been used to treat herpes successfully include
acyclovir, ganciclovir, cidofovir,
and feline or human interferon.
0.1% idoxuridine eye drops applyed to the affected eye 6 times per day long term. This is an eye drop that can be made by a compounding pharmacy.
Your vet can give you prescriptions of the above.
These will hopefully control the herpes infections and make your cat more comfortable.