The fluid reservoir is sectioned in two parts. The front part is for the brakes, and the rear one inch nearest the firewall holds the fluid for the clutch. First, make sure that the rear part of the reservoir has fluid in it. If it does have fluid, and you don't see any fluid dripping anywhere, then it's probably your clutch slave cylinder, which is mounted to the transmission, or your clutch master cylinder, which is mounted to the firewall. Note that the clutch master cylinder is different from the brake master cylinder...there's no need to go changing the brake master cylinder for a clutch problem.
Also, if you're looking for a leak, the clutch hydraulic system is very easy to track. At the back part of the fluid reservoir you will see a black flexible hose leading to the firewall and attaching to the clutch master cylinder. Look for leaks there and inside the car against the firewall where the clutch master cylinder (cmc) comes into the car. From the cmc there is a hard steel line that goes along the driver side to the front of the car. Attached to this is another flexible line that goes to the slave cylinder. Look for leaks along all lines and at the slave.
I just replaced my clutch master cylinder because I had similar problems to you, but I had no leaks anywhere and I had bled the system many times. Replacing the cmc corrected the problem and the clutch pedal is now back to normal.