04 kia optima

I have an 04 optima with a standard transmisson, clutch went out in 08 and had a new clutch put in. last week I wad driving and the clutch slipped when I was going up hill or accelerated hard. Now It takes off fine and drives fine, Just when it get to a hill out accelerate hard does it slip. Heres the question. IS there a way to tighten up the clutch so it catches? Or is it real hard to put a new clutch in?