Files were not attached to the survey

assuming the recordings (in this case) were not uploaded to the survey, is there a way they can go back and upload the file again, without losing the data?

You can do this by providing them the edit link, first you need to get the submission ID, this guide will help you to do so: https://www.jotform.com/help/549-where-to-find-the-submission-id

Then you can replace the "XXX" with the submission ID on this link: www.jotform.com/edit/XXXX

You can then provide the link to your user and they can edit the entry, upload the files and save the information on the same submission.