I don't think there's a default expiration or a retake link, other than any expiration date that may already exist for the survey in general. I've shared retake links with respondents previously and they've used them days or weeks later.
The bigger issue that I usually run into is getting respondents to understand that the retake links work differently than the original links. They can't resume where they left off if they close the survey in their browser; they'll have to start all over.