I have an 04 Mini with 31K miles and the other day when I got in and went to depress the clutch pedal was soft and it went right to the floor. I went to this forum and someone commented on a different post that the power steering and clutch share the same reservoir and that all it might need is fluid. So I checked and sure enough it was low so I added some CHF11S fluid to it and after a little work the clutch came back and everything was working well again. Two days went by and I went to drive it and the clutch pedal went right to the floor again. I was able to get it into reverse and once the car was driven a little bit the pedal returned to normal. I checked the fluid when I got back from my ride and it was still at the max level. Any suggestions what this could be or what to check for ?
Could there be air that got into the system?

Thanks in advance for any help, Tom