new unwrap from a existing one

Hi, i make models in sculptris that after i work in blender…sculptris export a mesh in obj file and a texture map whith the colors. then it can be inported to blender to continue working whith. i have now the model texturized on the 3d window (i can see it in real time cause i work in lgsl view) the problem comes from that sculptris makes a automaticall unwrap that works to load but is very confusing to work whith it cause have too much islands…so i make a new unwrap in blender whith the smart UV project…that gives me a far better result that the sculptris one…but the proble is:
How can now trnslate the texture map from the sculptris one to this one new made by blender…what i can see in the uv map window are the vertex but not the images of the old texture map fited to the new one…any idea?

In the render panel you have a Bake panel. You can bake a texture from one object to another object or from one object UV set to another UV layout.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Bake