Top it off for good measure, but it will likely make no difference in clutch travel. You've got a leak somewhere, most likely a bad master or slave cylinder.
Look at the carpet around the clutch pedal, pull the carpet back and look under it, if it's wet, you've got a bad clutch master cylinder. Also, follow the lines coming from the master cylinder (the thing with the fluid reservoir attached to it) until you get to the clutch slave cylinder (a small piston that actually engaged and disengages the clutch) and look for any moisture or fluid there. If there is any, that's where your problem is. If either of these things are bad, replace them IMMEDIATELY; you could be left with no clutch at any moment.
If there is no sign of seepage or leakage from either cylinder, then try bleeding the clutch. The process is identical to bleeding brakes; you'll find the bleeder valve on the slave cylinder.
If that doesn't seem to fix things, well, you got 90k out of a clutch that you say was abused. That's pretty dang good.