There's really no reason to register unless you are planning on breeding her. The only reason I registered Joey is because he was with the AKC, and I believe in the club, and what they are trying to accomplish, so my registration money was just my way to show them support. They also have a lifetime lost and found option that I found reassuring. Since the AKC has cracked down on breeders, many alternative registries have popped up and the CKC is one of them. They will register just about any dog, including mixed breeds, and this service is more so that breeders can advertise their dogs as "registered", but I don't feel that it adds any real value to the dog, because anyone can register their dog, at any time, so what's the purpose? No documentation is necessary, and they will take the breeders "word" for whether or not it's a purebred. Here's a link to registries that explains some of the difference.
Registries In essence, unless you believe in the club, and want to give them financial support, there is no real purpose of registration.