Richardson, who left his role as manager of Accrington Stanley last summer to become Paul Cook's deputy, had a year remaining on his previous deal. He had no hesitation in extending his stay at the Proact.
"The club's ambition matches mine and I am keen to help Paul Cook achieve further success after winning League 2," said Richardson. "With the tremendous backing we have received from the board, I can only see us going forward as a club and it's great to be a part of that."
Chief executive Chris Turner points out that Richardson's new deal ties him to the club for the same period as Cook. He said: "We have a great management team in place and we felt it was the correct decision to ensure that Paul and Leam were both secured on contracts until 2016."