When a survey closes, it is possible to re-open the survey and continue accepting employee responses, or send it out to more employees. To do so, follow the steps below.
Find your survey on the Surveys home page and click "Edit"
This will take you the the surveys "Share" page which contains details about the survey recipients, email invite, and survey/launch expiry time.
Scroll down to the "Schedule" section. Beside "Expiry Time," adjust the expiry date and time to when you'd like the new expiry details to be.
Once you've selected the new expiry date/time, click "Update" to update the expiry date. This will re-open the survey.
To learn how to add employees to a live survey, check out this article.