I'm not sure that any of the responses here answer his question.
To my mind, if the pedal used to be stiff and now it is soft, then somebody has introduced air bubbles into his clutch hydraulic lines. When he pushed on the pedal before, he was trying to compress fluid - when he pushes on the pedal how, he's trying to compress the air bubbles. Compressing air bubbles is a lot easier than compressing fluid, hence he has to push farther on the pedal before the air bubbles compress to the point that the fluid starts doing its job.
If slapping in a new clutch involves mucking about with the hydraulic lines, then maybe the mechanic just did a crappy job of bleeding it.