Keep the vine healthy well fed and watered, give it room to run up and enough sun. They can withstand the caterpillar attack and get beyond their capacity to damage it. It may be possible that the stress stimulates fruiting. Good luck!
i think it depends on the passi variety and caterpillar.
i have grown incarnata several times... usually, very healthy, at least 30ft of vine
almost every time each leaf was down to a nub in a few weeks.
at first i would kill each one, then it was just too much .
usually the plant is overcome in fall, and in winter (here) they often die back to the ground anyway.
try attracting birds, lizards, other predators.