His behaviour pointed to high risk areas "while he contemplates his sentence".
"The high risk areas in particular are conduct issues, negative attitudes towards authority and problem solving and the influence from negative peer associates," the board said in its decision.
"He has done a focus programme which did help him acknowledge his offending and develop and maintain motivation and practice good social skills with others."
It added: "It is essential for Mr Smith to make positive efforts towards making better decisions and having positive relations with staff."
Smith was "a young person with a particular developmental problem", the board said, with his "attitude and behaviour" being blamed for him not receiving any treatment in the four years he's been in prison.
"That unproductive four years has not helped anyone involved in this tragedy but hopefully if Mr Smith plays his part by co-operating with present staff thereby showing remorse, some gains for everyone can be made."
It was "essential" that a psychological assessment be carried out as soon as possible, the board said, and for the prison to implement any recommendations which arise from it.
"We note the sentence end date is 10 January 2016, so there is not a lot of time for productive work to be done, hence our concern that the assessment be carried out as soon as possible."
Mr Lewis' family had "made plain to us" their view on Smith and what they perceive as his lack of remorse, the board said.
His father Peter Lewis has previously said he believed Smith had "shown no remorse", and described his quick parole hearing as "another kick in the teeth for the family".
However, the Parole Board said it believed Smith was remorseful.
"He has assured us today that he is sorry for what he did, but I think it is also fair to say that he feels frustrated that he cannot really express it, at least verbally," the board said.