Once you have created the album you can select "Copy from past release" as the upload method. This will bring up your entire catalog and you can search for the name of the track or artist. You can select multiple tracks through this tool and then click add tracks.

All the previously used metadata such as ISRC and credits will be copied over as well as the wav. You will want to make sure that the "Has this track been previously distributed" box is checked yes and that the original release date is proivded. Your release will be rejected if the original release date is not provided on the track level.