Intermittent clutch slip or something else? Has been occurring for 2-3 years.

What is your question?

When releasing the clutch into 1-3rd gears my SUV shudders. It does not happen all the time, but seems worse when the car is warmed up or we've been driving for a while. I've taken it to two repairs shops and they've suggested it could be a worn clutch but there are no other indications that the clutch is going out... and this has been happening for 2-3 years. It is now getting worse. Any other suggestions? We just replaced the spark plugs. I don't want to replace the clutch unless we're out of other options since this clutch replacement is over $1700.