Your problem may indeed be due in part to air in the hydraulic system, however it can also be due to misadjustment of the eccentric bolt that connects the clutch pedal to the push rod of the clutch master cylinder.
Access to the eccentric bolt requires removal of the cover panel beneath the steering column. If the plastic end of the pushrod has not split or is otherwise damaged by wear, there should be enough adjustment available in the eccentric to completely remove any free play in the pedal. If you are able to, remove the free play, then back off until there is approx. 1/4 inch of free play at the pedal, and lock the adjustment.

A caution is in order here: the push rods are available in 2, perhaps 3 different lengths. If one has been installed that is too short, it will not be possible to properly adjust the free play.