Pages to Clone

We have several websites that we need to clone. We have the master code for the site and want to swap out the name of the city we use on each page for another city. The pages are done in very effective on page SEO and clean up online. We have several projects that we need cloned out. The projects run from 100-400 pages each and we have one that will eventually be 20,000 pages or more. We have several clients and can get many more but the way we clone our pages now is taking us away from other faucets of our business. If we can find a go to company to clone these for us we will have consistent business for you. Please let me know what you can do for us.