The clutch will wear on the fiber plates, the steels being harder don't wear as much. I have pulled a few clutches apart and most have no measurable wear. One was worn a bit, maybe half way down. It still worked. The fiber as it wears will just make the oil dark.
What oil are you using? This can cause slipping. Motorcycle specific oil has a JASO MA rating, some deisel oils have this rating, some don't. This rating means the oil has been tested and approved for wet clutches. An oil without this rating maybe ok to use, it may let the clutch slip.
Adjusting the cable just a bit tight can cause slipping to.
I would start with adjusting the clutch and cable. If this don't help and the oil is ok then you may need to tear the clutch apart and clean and measure the plates. Roughing up the fiber and steel plates with 80 or 100 grit sandpaper will help a bit, make them grippier.
Making sure the clutch is assembled correctly with the hole in the edge of the pressure plate lined up with the dimple on the hub. See the dimple through the hole. Maybe installing heavier springs.
If it still slips with all this then maybe you need new fiber plates. You can get the stock plates from the dealer they used the same plate in many bikes. Up to 2007 I think and on bikes like the 1700 cc road sofas.