I have wondered about retrying Cimzia. It was the most successful biologic I have tried so far.What about Simponi, Stelara or Entyvio? Even if you've taken Stelara before, now that it's approved for IBD, you may be able to get a higher dose. You can also add Methotrexate in place of Imuran.
You could also re-try something you've been on. It doesn't always work, but sometimes it does. My older daughter is on Humira for the second time and it has worked just as well for her.