Trip drain lever doesn't stay up

I have a trip drain in my bathtub that does not stay in the up postition to drain the tub. What is supposed to keep the lever from dropping? Do I need to get a new trip plate and lever?

tension screw

depending on the kind you have there should be a tension nut or screw on the back side of the leaver to hold it in the up position. If the tension adjustment is not there look for it elsewhere on the stopper assembly. If you dont find one I would replace it with a better quality one from a supply house rather than a home center. Hope this helps.