Could be air in the system or failing seals. Suggest looking under the dash and looking for any hydraulic fluid around the clutch master cylinder or under the rubber boot. If there is any, you should reoplace the clutch master cylinder. If you don't see any obvious leaks, try bleeding the clutch system. It's not too hard to do if you have some jackstands anfd a friend to help you. This is something that can leave you stranded if it fails completely.
Do you notice any difference in how it works? as opposed to just how it feels?