It could be an oil problem. Either contaminated oil or low oil maybe. Also I do remember an issue with some KTM’s where the clutches wore out quickly because an oil jet inside the clutch casing either got clogged or was faulty and the clutch plates got starved of oil. Rekluse make special clutch friction plates (called Torque Drive) which circulate the oil better. I have them on my Harley and they work well. It might also be a weak/faulty clutch spring which is causing the slipping.