The release of victim names to the press is handled by law enforcement officials (city, county (parish if in Louisiana), state or federal). The common accepted rule is that the name of a victim is not released until next of kin has been notified by law enforcement officials. After the next of kin notification is made, the press is given the name.
The fact that she was a juvenile has no bearing. If she had been 82 years of age, they would still withhold the name until the next of kin notification. Obviously, no one wants to learn about the death of a loved one via the press. Also, law enforcement officials need to assess the impact of the death notification on the immediate family to curb possible suicide attempts or other domestic violence.
Do we need to know her name? Yes we do. After all, we know the name of 4 year old Agnes Bamuwamye. The First Amendment to the United States Constitution provides that "Congress shall make no law...abridging the freedom...of the press."