[morethanpretty]

There are a lot of factors that go into making that decision I think.
You have to consider how long its been since ya'll parted ways.
Have you completely healed from the pain of the breakup.
Have you forgiven her completely.
If it happens again (a lot of people suffer relapses and setbacks of old habits/behaviours) will that end the relationship again.
She is doing "better" but depending on how bad she was doing before, she might still need the emotional support of a social worker/father/companion. Are you willing to be that again.
Consider that she might not be ready to start/restart a relationship because she's still somewhat emotionally unstable.

Yes I think it is perfectly reasonable to try to "fan an old flame." I think before you try again, you need to make sure you're emotionally ready for it. I think all relationships should get a fresh start, new or rekindled. To me, since you say never were able to get over her, I think you're still harboring some of the past regret/pain/ect. You need to make sure ya'll get a fresh start. How hard have you tried to move on? How long has it been?