Hi there,
Unfortunately, the link expiration date cannot be changed for a mailing once the survey links have been sent. If a respondent attempts to initiate the survey session after the link has expired, they will not be able to take the survey. If, however, the respondent logged an incomplete survey response before the link expired, they will be able to finish the survey after the link has expired per the incomplete survey response settings.
https://www.qualtrics.com/support/survey-platform/distributions-module/email-distribution/emails-overview/#DistributionAndSurveyExpiration
So I think your best bet to get survey links in front of any non respondents is to issue them brand new invitations. I would recommend making a new panel of non respondents and sending them invitations using the Qualtrics mailer. Including "Reminder" in the invite's subject line should work to keep up appearances.

Tom_1842 Thanks for your response! You mentioned panels - we don't have that feature as part of our package. Do you know if I could just create a new distribution list and send it that way? Will that allow me to give them new individual links once their initial ones expire?

Hi mmercer yup uploading the non respondents as a new Contact List (this is what our org uses) and sending new invitations to this Contact List will give them fresh links to take the survey

Tom_1842 Thanks so much! I appreciate your collaboration and time!