well the only thing they can really use is the whole Isley telling Raki "i will see you again" from the end of the anime , while not sure how , at the same time its the only faint clue we got about a 2nd season
prehaps make it so Raki somehow gets separated from Clare, and enRAB up in Isleys care again (of course the very fact that the end of the events that happened in the anime, mean that things such as the battle against Lucellia never happened or atleast would have to be delayed)