for a clutch to be on its way out, it will start slipping in 4th gear, foot to floor, full boost, after getting hot, but it starts off, only when hot, then goes to all the time, and now for eg myn, slips in 3rd, 4th and 5th when i hit full boost...
if your release point has only recently changed then try getting a rebuild kit for your master cylinder as the seals may be warn and it might not hold full pressure.