Thanks to CorFidele for this:
Michael Ausiello, of The Ausiello Files over at Entertainment Weekly, answers this question from his most recent Q&A session:
Question: I have a mad crush on Gabriel Byrne. When is “In Treatment” coming back? —Tara
Ausiello: Negotiations to bring the show back for a third season are taking place as we speak.
Tara, we are with you. Keep your fingers crossed, everyone!