It comes just a day after teenage striker Craig Moore agreed an extended deal until the summer of 2016.
Lasley - out of contract this summer - has agreed to a similar stay. "It has been no secret I wanted to stay here and hopefully we can continue the great run the club has been on," he said.
"I am delighted to sign on again and be a part of what will I hope will be another few successful years."
Manager Stuart McCall said: "I am absolutely thrilled. Keeping Keith at the club was imperative."