Rose - I think the next step would be to reduce her dose to 0.1u. She's had a week of normal numbers at 0.25u, so you can reduce and try the 0.1u. Pics in the sticky of what 0.1u looks like. Fingers crossed that she holds the reduction.
Cassius - yes, you've had a week in all normal numbers on the 0.5u - so you can also reduce him and try 0.25u.
Poor Mikey - I hope he feels better. If you need a reminder on what to ask for at the vet's, Marje's post on p-titis is in the "new to the group?" sticky, in the last section of single topic posts. Sub-q fluids, anti-nausea meds, possibly appetite stimulants, vit B-12 shots are all things that we used with punkin that you may want to ask about. Pain relief is also really important - p-titis is painful. Most people get oral buprinorphin (bupe) and squirt it into the cheek pocket or up on the gums, under the lip. It absorbs very quickly through mucous membranes.
If you end up doing sub-q fluids, you may want the kind of tubing that has a port so you can add the vitamin B shots into the port instead of a separate poke. We bought tubing and needles from thriving pets. They have great customer service - I called and they helped me get the right thing.