To update your widget, go to your Order History, and click the 'Make a Correction' link. You will then be prompted to make changes to your widget.
Once you've finalized your changes, click 'Save and Recreate Order'. The widget will now take 5-10 minutes to update. Check back on your widget at signagelive.com, to find it updated.
You are not required to re-download or re-upload the widget, as it will be updated once the changes have been saved on PosterMyWall, and the order regenerated.
To learn more about Signagelive, check out this page.