Copy the rhcolor.apj file to new project.
Thank you for this, Peter Grainge. Having just added several colours from our new corporate palette to a current (RH 2015) project, I foolishly expected there to be a way to import them into other projects. No such luck.
I discovered from version control (SVN) that the file must be rhcolor.apj, but didn't know whether I could safely copy it into other projects. Now I do. Thanks for saving me some stressful experimentation. :-)