If you want to give him two more cycles, you can but don’t let him stay at the current dose more than six cycles total. Your vet has shown in the past that they don’t understand how the insulin works and I’m sure they’ve not dealt with potentially high dose cats.
Here is the SS of a high dose kitty where the dose was increased in the same way we are doing Biscuits.
You hold the syringe. At some point, we need to take six cycles between increases. It Wendy and I discussed that it was better to wait u til we at least see pink. OTOH, he’s been high a long time so two more cycles for a goal of six at this dose is not the end of the world.