Yes, it is possible to resend a survey invitation and exclude people who have already responded to your survey. You can either create a new invitation and insert a survey link from the Insert drop down menu, or copy your old invitation, delete the survey link, and insert a new link using the Insert drop down menu. Preview and test your email as normal. On the launch step, look for the recipient summary section, and choose "Email only those recipients who have not completed the survey." Click on the "Recalculate Recipients Total" link to see your updated total. Click launch to resend your survey invitation.