If you have a yard with secure fencing, then adding a layer of non-electric cat proof fencing to the top may be the answer for you. While cats can scale most standard wood, wire, and brick fences, cat proof fencing adds an extra layer of protection to keep kitty in. Kits begin at around $100, depending upon the type and size of your yard. Or you can make your own.
The disadvantage is that this is the least secure form of outdoor enclosure. Other cats can gain access, exposing your cat to injury, parasites and disease. Also, such fencing will not keep out predators such as owls, hawks and coyotes, or people intent on mischief. Some authorities recommend constant supervision when the cat is outside. Too much can happen when you're not looking.