You uploaded your entire customer list a few month ago and you set up "automatic mode" to run your feedback request campaign. Today you received an email that "All Feedback Requests have been sent".
1- Add more new customers. Upload your latest customer list.
2- Manually Resend a request to those from previous month that have not yet responded. Note GatherUp will ask only two times for feedback when using automatic mode. Using manual mode allows you to ask for a third time.
3- You might consider putting the Feedback URL in all correspondence feedback. More here.
4- Getting a card printed with your feedback URL (perhaps shortened) and handing out the cards to front counter folks
1- Add Facebook and Google instead of another less common provider as a review site as more people are likely to leave a review
2- Change your subject line (feel free to test more but subject line is critical for getting emails noticed and open) from Thanks for your business! Would you leave us your feedback? to A Huge Favor. Would you leave us your feedback?