Harun Jama was found with stab wounds in Friar's Wharf.
The 16-year-old, from Birmingham, was knifed in the stomach, leg and chest on 3rd January.
He was taken to hospital for treatment, where he later died.
Police investigating his murder have made a number of arrests, gathered 700 statements and 1000 exhibits.
But, The Force is now re-appealing for people to come forward with information.
Hibo Fidow is Harun's mum:
Senior investigating officer, Detective Chief Inspector Andy Howard, of Thames Valley Police's Major Crime Unit, said: "We have spent the months since Harun's murder carrying out a full investigation and pursuing several lines of enquiry.
"We believe that there could have been several people who witnessed this incident who have not yet come forward.
"These people could have information which is vital to our investigation, and which could help to bring offenders to justice."
Police have described Haruns's death as 'needless.'
A 33-year-old man from Oxford was charged with murder and drugs offences in connection with the investigation. However, the murder charge has since been discontinued.
A 25-year-old woman, also from Oxford, was charged with drugs offences and released under investigation.
Detective Chief Inspector Andy Howard added:"If you were in or around Friar's Wharf that evening, or saw anything which you think could help our investigation, no matter how insignificant it may appear to you, I would ask you to come forward.
"We remain dedicated to finding those who are responsible for Harun's death and bringing them to justice.
"If you think you can help us to do this, please call the Thames Valley Police non-emergency number on 101."
Witnesses can also report any information online, by clicking here.