You can make use of our Save and Continue Later feature for this purpose. This feature saves the progress of the survey so the users can continue the survey at any time, without losing their responses. The respondents can come back later and update their responses even after submitting the responses in the survey.

There is also another way to enable your respondents to save and resume their responses. Once you enable Prevent Multiple Responses in the Launch> Restrictions menu and allow your respondents to update their responses, they will be able to access the survey at any time with their unique URL and update their responses.