Do you know what variety they were? There's a few that are cold hardy but I don't know if there's any passiflora that is hardy in your zone. I'd just cut back all the dead vines and see if they come back from the roots.

Well, no matter what kind they were, removing the dead vines won't impact whether or not they come back or not. If they were incarnata, you've got a chance at them regrowing from the roots. Possibly caerulea as well. But it depends on your climate zone.

If you don't know what kind you had, can you point out a photo online that looks like your plant's blooms? That'd help a lot, since there are dozens of passiflora species and hybrids that are common in the U.S.

I just suggested removing the dead growth for asthetic reasons. Who wants to look at a bunch of dead vines. lol Upstate NY can get pretty darn cold, zone 5 maybe???