Around here, you could not kill incarnata with a weedwhacker (or a flame thrower!), as the runners go all over the place underground. I mow them all summer, and they just pop back up within a couple of days. If it was more recent, I would say they are just dormant, but 3 months now in your climate would suggest they are dead. I guess you won't really know until spring.

~kiwinut

I had a passiflora 'something' in a pot last year- Mistakenly left it outside over the winter & the vines all died. I pulled them in the spring & set the pot in the pike of ones to plant something in.. September rolls around and there's new growth in the pot. Took the roots that long to recover & get up enough energy to start sending up shoots.. Same thing with some caerulea I moved. Roots had grown through the bottom of the pots so I had to hack them loose to move them. About 6 months later there's caerulea vines coming up all over where the pots once were. So don't give up hope- Only time will tell if it's really dead or not.