It'll be interesting to see what you get for day tests this weekend. Maybe you can find out when her onset and nadir is on Lev. I also think that if you don't see some blues tomorrow, you can take up the dose tomorrow night. You lowered it lower than we normally would for a kitty switching from Lantus to Lev, and she wasn't at her good dose of Lantus yet.
I also think I'd increase her dose tomorrow. The main reason for decreasing with the initial dose is because a small number of cats have a dramatic response the first day. Since she's demonstrated that didn't happen, I'd increase the dose. I might even go to 12u and see what that does for her, but of course, i'm just throwing out an idea and the choice is yours.