1993 Toyota Paseo clutch

Okay soo, my clutch has pretty much been perfect since a bought the car at 79000 miles. But in the last two months it has slipped just a little bit, really not a problem at all. However recently I had not checked my clutch fluid level and must have run really low because shortly after reaching fifth gear on the highway my clutch pedal seemed to stop working. Complete freeplay in both directions, though the car remains in gear and can continue to drive. So I slow down pop it out of fifth as I slow down and pull over; I had a feeling it was the lack of fluid so luckily my friend who was in front of my had some dot 3 to fill up my clutch fluid reservoir. After doing this and pumping the clutch a couple times it seemed all cherry. Now two days later it seems that once I reach fifth gear the clutch pedal will go out the same way as before (complete freeplay in both directions). And when I pull over, turn off the car pump the clutch a couple time and then start up and go the clutch works fine untill fifth gear again. Any ideas thanks,
Theo