Benitez admits the performance in the opening 45 minutes against Middlesbrough was simply not good enough.
He told Liverpoolfc.tv: "The first half wasn't good enough. In the second we had chances and the team changed a lot. The mentality and the attitude was better.
"We know we must improve. Clearly we talked about this after the game, but the players know when we have played badly. The mentality and the attitude must always be 100 per cent commitment, must always be 100 per cent for winning from the first minute. We must think about this.
"All of us need to improve. The players know that some players are playing well and scoring goals, so we need to see the other players doing what they were doing at the beginning of the season when we were scoring goals from everywhere. The players and the staff know we must play better and give the fans more. We will try to do that against Luton at Anfield."
Benitez admits confidence has been affected by a run of four straight draws, with his side yet to record a victory in 2008.
"It's clear we need to take our chances and kill games," he added. "The quality is there. We were playing fantastic football at the beginning of the season and also in some of the Champions League games. The football is there, but maybe it's a little bit of confidence that we need at the moment.
"When you have chances and you don't score, everybody starts talking about how we got another draw, so the players can maybe lose confidence. But it's simple how you can change this: winning, scoring goals and playing well. We will try to do these things against Luton.
"We won in the last minute against Derby but the mentality was good, against Man City it was the same. The team was always creating chances. Against Wigan it was different but we still had seven or eight clear chances. So, every game we've had chances. We need to take those chances and then the confidence will come back."