He may not get four more years, but Richard Nixon is now certifiably a hit on Broadway. Peter Morgan’s political character study “Frost/Nixon” grossed $512,604 last week, pushing the production into the black to earn back its $2.5 million capitalization after 14 weeks on the boards.The Brit transfer’s Aug. 19 final performance at the Jacobs Theater remains unchanged, due to the tight shooting schedule for the upcoming Ron Howard-helmed screen version. The film will star the play’s current leads, Frank Langella and Michael Sheen. Langella’s performance as the 37th president won him a third Tony award. The show’s national tour will begin in the fall of 2008.