1993 Isuzu Rodeo Question Clutch problems

About once a month, I have to fill the clutch master cylinder with fluid as it gets very low; still visible in the reservoir though. No leaks in my driveway, or where I park at work so I have no clue where the fluid is going. Over the past few weeks, my clutch pedal seems to have dropped quite a bit and feels soft. It is very difficult to get into gear and almost impossible to get into reverse. One funny thing I have noticed is that after driving for a while the pedal gets more feel to it and shifting is much easier, even reverse goes without problems.
My question is this:
Am I looking at a clutch replacement or a master/slave cylinder replacement. Or all three. Any help would be greatly appreciated.