I also had a new clutch on my 1.4 k11 and over two years (111,000-137,000miles) the clutch pedal was progressively getting very stiff.
My gearbox recently needed to be changed due to main bearing failure and I noticed that the clutch lever, which is a attached to rotating shaft within gearbox, was much more free to rotate on the new gearbox.
I lubricated the new gearbox shaft prior to assembly and yet another new clutch. The last one looked overly worn which was likely due to the sticking shaft.
The clutch now feels great. Very light and much more feel. Car transformed.