If your daughter has contact with law enforcement and is on probation, the police will notify probation of the contact. That can lead to a violation, because that's what probation is supposed to do.
That said, however, just because probation has to lodge a violation does not mean that your daughter would be at serious risk of revocation of her probation and resentencing. She is a victim here, and at any violation hearing before her sentencing judge, that's very important.
If your daughter was doing something wrong in even seeing her ex, then legally she would be on shakier ground. But if she's simply a victim of an assault, that's not something for which probation would likely want to revoke her.
As she does have a public defender who was assigned to the underlying case for which she is on probation, she ought to contact him or her, but I see nothing here in your fact pattern that would make probation unwilling to work with your daughter any more, and as long as they are willing to keep working with her, she'll be able to avoid jail.
Was her ex arrested for the assault?