Your original remains intact -- all the repairs are made on a digital copy.
A print can be made from the digital file, or the file can be written to CD.
Each individual project is different, so each project has to be seen and evaluated before an estimate can be made. It can be relatively expensive ($50 -$150 is not unheard of), but it's definitely worth it when the image is important.
Please contact me to make arrangements for that estimate.