Hi Lindsay - as you know, we really depend on those mid-cycle numbers to make dosing decisions. It's pretty close to impossible to know what's going on by just looking at the PS numbers. I do think though that lowering the dose would be better than needing to skip (I agree that you made the right decision this morning since you couldn't monitor), so if she's high enough to shoot in the morning, go ahead and lower to 1.25u. I think lowering 0.5u might leave her in numbers that are too high, so I would go with the smaller reduction.
In the bigger picture, just for future reference, when lowering the dose, you can lower by whatever amount is needed. You don't necessarily need to stick with 0.25u increments. My suggestion to do that in this case is just that I think lowering by more than that might not be enough insulin. Raising the dose it's more important to abide by the small changes to avoid making your kitty feel icky.