The 53-year-old, who has previously managed Southampton and Northampton, had originally joined Dave Jones' staff until the end of the 2012/13 season - but has committed his future.
He told the club's website: "This is a wonderful club and I have really enjoyed the role in the short time I have had at the club so far.
"I got the call from the manager last December to see if I could help out and I was delighted to do so.
"Sometimes another voice, a new voice, can have the desired effect and we have a great bunch of players who listen and respond to what the staff have to say.
"It's all about the future now and everyone is back for pre-season training. The plans have been in place for some time, with everything geared towards 3rd August in the Championship against QPR."