“Hairspray” is getting a major makeover. New Line has pushed the start date of the movie musical from this fall to spring 2006 and co-directors Jerry Mitchell and Jack O’Brien have left the production. The studio has drawn up a short list of replacements, topped by “Chicago” director Rob Marshall, and shifted its projected “Hairspray” release from Christmas 2006 to summer 2007. New Line confirmed the exits of Mitchell, who choreographed the stage musical, and O’Brien, who won a Tony for directing it. The duo had been set to co-direct since New Line announced its feature plans.