A Her Majesty's Inspectorate of Constabulary review in December 2014 found issues, including delays in investigating some cases.
Following a post-inspection review in August 2015, improvements were found such as more officers assigned.
However, concerns still existed over children still being unnecessarily detained overnight.
There were also worries over the timeliness of forensic medical examinations in child sexual abuse cases and children involved in online grooming allocated untrained staff.
Inspector Wendy Williams said that while she is "encouraged" by improvements, the force will continue to be monitored.
An NSPCC Cymru spokesman said: "It is clear there is more work to do and we remain extremely concerned at some of the inspectors' findings."
Det Chf Supt Andy John said the force continues to make progress against the recommendations made.
Concerns still exist over the child protection work of Dyfed-Powys Police, despite improvements in some areas.