Trina:
All I can tell you is that statistics quote that childhood ITP is acute 80% of the time. There are many children who never have a recurrence. Using that statistic, there would be a 20% chance that your daughter could relapse. Not having a crystal ball, no one knows which percentage she will be in. Knowing the numbers will not predict what will happen with your daughter.
My advice would be to forget about ITP and move on. If ITP recurs, cross that bridge when you come to it. There isn't anything you can do to prevent it.
If this helps, my sister had a similar situation. She had ITP for a year with low counts, went into remission after a year, and has never had a recurrence. It's been 29 years.