IMT not going into remission

My Qiji (key-chee) was diagnosed with IMT in December 2005. She was started on prednisone. After a few attempts at getting her into remission, we started her on Imuran. She finally went into remission and was kept on a maintenance dose of the Imuran. She was taken off of it after approx. 8 months with one or two breakthrough relapses. She has relapsed several times since stopping the Imuran. The latest relapse started in March 2009. She has had ONE platelet count that was within normal limits. She has had skin issues. Thinking probably pyoderma from immuno therapy. However, they start as little teeny tiny black spots *pore sized*. The spots are combed or brushed off into flakes. The black spots are replaced then by red (blood) ones. A day or two later they are raised (pimple-esque). I can usually tell when her count is low because of that and she becomes less active.
Since we cannot have her on suppressive therapy anymore and she refuses to take medicine anymore, I think we are looking at limited time. Is there any indicators/parameters you would go by to determine euthanasia in this case? She is slower and does moan at times when you pick her up or hold her, but in general, she is her normal self. I just keep thinking "What if she gets better?"
Any help is appreciated

[Jim Humphries, B.S., D.V.M.]

seems like you are asking the right time to make a difficult decision.  that is so different for every one and every case.  I think when life is more difficult than it is fun it is near time.  I also believe they "tell" us in many ways.  If she is "her normal self" then I think you are not near that time.  Dogs can hold their own a long time, and I've seen them go downhill quickly.  You and you alone will have to determine this and it is always a difficult decision.