If you're referring to the Space Launch System --- the Congressionally mandated program to build another launch vehicle with the Saturn V's capacity --- Congress has mandated that that should instead try to reuse technology from the shuttle program. But at this point, the "reuse" is looking a lot more like "redesign" --- the solid boosters changed most of the key components (casings, seals, propellants), and it isn't yet clear how much the "cheap, expendable variant" of the Space Shuttle Main Engine will have in common with its original variant.

There's some grumbling in space activist circles that the mandate is, at least in part, designed to keep federal money flowing towards the contractors for the Shuttle propulsion systems.

(That said, building a new Saturn V isn't as easy as dusting off the blueprints. Some aspects of the design would have to change --- there are places where the originals used asbestos, for example. And the plant where the first stage was build has since been reconfigured so that it can no longer handle anything that diameter. But there's a lot less technical voodoo involved than for that SSME refit...)