To import your photos from a previous listing, you'll need to edit your listing and go to Manage Photos.
If you haven't uploaded any photos, there will be a link that will let you import photos from another listing. If you have uploaded pictures from your computer and if the link is no longer there, you are able to delete those pictures to get the link to show up again. Recommendation is to upload pictures from a listing first and then upload any other pictures from the computer.
Click the link, enter the MLS, then click Import Photos.
Make sure to click the Save button once it's done importing.