The problem is this. From an outsider looking in, and from what you have put in your message, it sounds to me like she was not ready to give up in the first place, and the help she was getting was not constant. I would imagine if she tested positive for Heroin on a Methadone program, she will be back on the gear. (Heroin).
If she is, It is not a problem in respect of, just because she has failed to give up once, does not mean she will fail a second time. You are allowed more than one go at giving up.
She will contact you when she needs money, so hang in there. You will hear from her in time. Just don't be taken in by her stories and try and get her on a proper private scheme where she lives in. A day program will not help by the sounds of things.
Good luck