The only way you can get the reptiles back is to restore a healthy environment for them. I doubt you can blame cats entirely for their disappearance, but they undoubtedly contributed and they eat a lot of other native wildlife as well. Outdoor cats are a huge problem all over North America and it's difficult to get cat owners to take appropriate responsibility and governments to recognize the problem. The American Bird Conservancy's Cats Indoors! Campaign is working on this and could use your help!
Many reptiles also are killed by small, native predators that occur at unnaturally high densities around people because of easy access to food and the absence of larger predators; by automobiles; and by people who are afraid of them or just don't like them. Fixing these problems is pretty hard. The best thing you can do is share your concern with your neighbors and make your own yard as reptile-friendly as you can by leaving natural habitat, not using pesticides, and providing cover.