Cheryl Grimmer's family is damaged after the DPP upheld the decision to abandon the case over her 1970 disappearance.
The family says the review failed to adequately address more than 50 detailed submissions.
The family are considering an offer to meet with the DPP and urging police to follow alleged new evidence.
Cheryl disappeared from Fairy Meadow Beach near Wollongong on January 12, 1970.
The review examined the decision to discontinue proceedings against a man known by the pseudonym "Mercury", who had been charged over Cheryl's disappearance.
The prosecution collapsed in 2019 after the NSW Supreme Court excluded admissions Mercury made to police when he was 17.
Justice Robert Hulme found the interview did not meet legal requirements applying to admissions made by children, including safeguards concerning the presence of an adult.
In a two-page letter emailed to the family on September 16, director of public prosecutions Sally Dowling SC acknowledged the impact of the original decision and their patience while the review was conducted.
"As you appreciate, this question turns on whether the exclusion of the recorded interview with Mercury by the trial judge is reasonably open to challenge."
Mr Nash said the family had provided 50 detailed submissions, setting out extensive evidence and legal arguments.
Mr Nash said the repose provided little detail explaining how those matters were dealt with.