I recently got my clutch replaced(~500 miles ago) in my 94 GS-R.

After daily driving and breaking in the clutch for 300 miles, I figured it should be ready to have some fun. When I try to race, after I shift at around 8k and hit 2nd, the clutch doesn't seem to grab, even though the pedal is all the way out. The RPM's Stay at about 7k rpm for a second or 2(while I am flooring it) and then they climb to 8k and I shift, the exact same thing happens for 3rd gear.

I figured this was just because the clutch wasn't broken in yet, but after 500 miles I think it should be better? My clutch is a brand new OEM GS-R clutch.
any ideas?