I admit not knowing anything. I planted a vine 3 years ago in a sunny location and watered on times. up sprung a big vine with large purple flowers that bloomed and died several times spring to fall. it ran out to 20 ft.

looked at this plant this AM and it is definitely looks dead, from soil line to the tip. not a bit of green on a leaf or branch or stalk.

before when leaves or branches looked dead I cut em off only to find out that the leaves come back and even flower on branches I left alone.

so should I cut it back to soil line or simply leave it be.?

Try to cut one stem at a time and look at the cut. If it is green inside it is alive. Start cutting pieces from the top and move down. If all stems are dead do have hope. Sometimes that happens with clematises. They usually come back next year.