Board Thread:New on Battle Pirates Wiki/@comment-76.107.30.53-20131016190446/@comment-17733617-20131017003834

Retrofit Lab only changes the blueprint & all ships using that blueprint.

If you have a standard BB & which you would like to be a BBA, you will have to build a BBA and scrap the standard BB.

Unfortunately Kixeye has not introduced a way to upgrade standard hull to advanced hull.

Hope this helps, if you have any more questions just ask.