Lost connection during last stage of Santini challenge

Is it possible to continue a partial workout? My laptop froze with 0.9 miles to go in my stage 4 Santini challenge. The partial file shows me at 2 miles to go but regardless, I’d like to be able to simply complete the challenge as opposed to having to do the whole ride over again this week.

Is there anything I can do?

Not that I have heard of, you might want to submit a ticket with your log files: https://support.zwift.com/hc/en-us/requests/new