If you do prune it back, I wouldn't dig it up. It won't hurt anything to leave it there. You never know, it could very well come back, and not necessarily in the same spot. I have them coming up everywhere, now, except the spot I have had them for the past three years, which is the spot I planted them the first year.

Didn't Washington have an unusually late, persistent winter this year? Caerulea is pretty tolerant of cold, wet weather--it does very well in the U.K., after all. Are the vines still green? Or have they dried out and dessicated? If the vines are still green and firm, I wouldn't worry. It's likely gone dormant because of the late freeze and will rebound with new growth sooner or later. If the vines are dead, prune them back. Caerulea will normally regrow from the roots.

If you get into June with no new growth, however, I'd say it's time to accept the worst.

Hey, you just never know-it may come back up yet. I don't want to get your hopes up but I have to tell you-I'm up here in cold Canada and left my Caerulea in the ground over the winter by accident (totally forgot to bring it in before the winter) anyways, for the next three years through snow, slush and hard winds-it came back up strong and hardy each year with fruit (though it never ripened). So, hopefully yours does come back. I'd just like to add for all of you down in the warmer states--you're all very lucky to be able to grow this wonderful plant without greenhousing.
Anyways, good luck-hope it comes back for you.

In an average year my hardy passion vines don't come up until June. This year we had an unseasonably cold, long winter so if mine did survive I won't expect to see them for several more weeks.