Honestly, the best way to convince your parents is to not say anything at all. Parents HATE to be nagged! Try to keep up your grades, keep your room clean, and help out around the house. But don't kiss up, it's obnoxious. But you really need to try and see things from your parents point of view. Your last puppy didn't work out, that's discouraging and dissapointing. So why would they do that all over again? Puppies do cost money, not only the upfront payment but vet bills, food, and flea,tick and worm preventative. Not to mention bathroom breaks at 4:30 in the morning anf the whining and crying. As tempting as puppies are, believe me they are tempting to have, your parents might be more willing to get an older dog. That's right, adoption! There are over 2 million great dogs waiting on homes. And you don't have to go get a mutt from a shelter (although shelter dogs do make the best dogs. Many of them are put down every day!) If your looking for a specific breed you can search for breed specific dog rescues in your area. For example, my mom is the intake coordinater for a golden retriever rescue. You should at least look into it. Many of the dogs are grown, already house trained, evaluated, and have had those pricey puppy shots, and they are spayed/ neautered. If you do end up with a puppy please avoid backyard breeders and puppy mills. Find a reputable breeder and always spay/neauter your dog. Best of luck!!
active in dog rescue and 4 dogs of my own