Yes, that sounds quite familiar.
My first clutch rebuild (in 2008) used all new OEM plates & springs, and Mobil One synthetic oil. That clutch slipped from the moment I put it in gear (which is why I asked about the oil). I re-used the springs & steel plates (fibers were ruined) with another new set of OEM frictions & Spectra 10W-40 dino oil, which lasted about one full season of riding before starting to slip in the higher gears. After that I rebuilt using all Barnett parts (slight slippage after a month or so), then rebuilt again w/all OEM plates & Barnett 501-29-06072 springs; this clutch still works perfectly over 6,000 hard miles later, on a heavily modified motor. I'm going to replace it now whether it needs it or not.
It would surely be best to rebuild your clutch completely using OEM plates & Barnett springs, but another option would be to sand all plates lightly w/400 grit paper and re-use them with new Barnett springs. If you decide to replace w/OEM plates and can't find them let me know, there are some later Honda plates that should work fine. Also, the clutch hub splines and basket 'fingers' should be filed flat if they show any notching (which they usually do), otherwise the clutch won't engage/disengage smoothly.
Ray