clutch

I had terrible clutch slip with my rover 400 deisel while towing so had a new clutch fitted in august. however am now getting clutch slip again after 2 months generally when the car is warm or been ticking over in traffic. problem hapens most at around 2,500 revs as the turbo kicks in engine speed inceases up to 5,000 revs but speed pick up is much slower is this normal? this is my 1st turbo car, but it deffinatley feels like clutch slip