There is a spring attached to the Lower Clutch Lever. That spring must have enough tension to bring the Handlebar Clutch Lever back to its free play position. If its too weak, it should be replaced, or you can try snipping off a small piece and re-bending the end to fit - that will add extra tension to the spring.
Also, when adjusting the Clutch Adjusting Bolt, be sure to turn the bolt out several turns before turning it back in. When turning it in, don't turn so far that the bolt stops - thats much too far. Turn it in until you feel a resistance. This resistance point is the point at which the Clutch Lifter Plate is beginning to disengage the Clutch disks. From this position, turn back 1/4 turn and lock it in place.