If you have cropped but stayed with the original aspect ratio then you don't have to do anything. If you cropped to some other ratio, do as Bob mentioned and undo the crop and use the original (3:2) ratio to see if that ratio will work with the image. Otherwise, your image will be cropped again during printing, or you can have it printed with wide borders on the short side.
When you click on the crop tool, look where it says Original - next to the lock icon. That's actually a drop-down menu, and you can lock the aspect ratio to some selected size, including the original one. Then when you move the borders around, they will both move in tandem.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!
There are 2 options to save your current edit + crop view.
1. while in 'Develop' module. Use the 'snapshot' option (on left panel) to saved & named your current edit/view. After you save this, you can go on to uncrop/re-crop edit etc...but you can come back to this view via your saved snapshot. 2. Create a 'virtual copy', and edit 1 of the copy for new use.