Of course you can.
In order to get your release online via MusicDigi please ask your current distributor to remove your releases from their service. Once this is done you can publish your releases again via MusicDigi. We recommend that you get your music offline before publishing it via our service since the digital stores are not big fans of duplicate releases.
You will also be able to use your old ISRC codes for your new release on MusicDigi. Just add the codes in the ISRC code section for your new release and your are set to go.