BladeDancer

I think Cat has been consumed by getting revenge on the Frey's since her 'return'. The only thing that would overcome this obsession with revenge is her love for her children. However she thinks they are all dead. Now Edric Dayne, and some other members of the BWB know that Arya was alive, so Cat at some point has to hear about Arya being alive. Cat originally released Jaime under Brienne's guard as he had agreed to ensure her daughters return in exchange. She will get Brienne to lure Jaime into her captivity and make him swear to fulfill that promise as a priority. However Sansa is still hidden in the Vale. So I doubt Jaime, Brienne and Cat will go there. But word will have spread South that Ramsey Bolton is marrying Arya Stark at Winterfell. So I think they will end up travelling to Winterfell to find Arya (even though she is fake).