you say it was changed 3 months ago was it slipping then basicly as the cable is used it can stretch that would cause you to have to push the clutch in thurther to make it disingage then you adjust it so the clutch disingages closer to the top of the pedal the only way the clutch could start to slip is if its knackered or the calbe has got shorter you could try loosening the cable but highly likely that you need a new clutch plate. do you drive like a racing driver or my dad as racing drivers wreck clutches my dads clutch would last 30 years