Some Real Racers will probably jump in here . . .

However, it is said that the way to get to ride faster is to ride faster. So try intervals at 30 mph or as close to that as you can get. Hold it as long as you can, recover, repeat. Say 2 sets of 3 on a moderate ride and after you're well warmed up. Really work on your aero position and form during these. Quit when you can't hit your speed any more. Crits are all about anaerobic efforts, recovering, and doing it again and again. So that's what you want to do. Try the "33" Road Bike Racing for better information. There's a sticky for intervals that's very useful and those folks are a mine of information.

You are doing great on your strong foundation. Chapeau!