Verified answer

First of all, you don't level up paradigms. You can add more paradigms, and level up your roles, but there isn't a way to level up paradigms.

Second of all, to get more of them you go into the menu once you are out of battle and go to the paradigms tab. Scroll down to the empty slots and either have the computer generate a paradigm for you randomly or choose your own roles for the characters in your party.