Teach your puppy a conflicting behavior such as “fetch your ball.” She can’t jump up if she’s running to bring you her ball or favorite toy. Just the name of a special game or toy—“go get your bear!”—can change the dog’s focus and redirect the behavior long enough for you to evade the jumping. With enough repetition, your puppy will begin to associate your home-coming with “go fetch” instead of jumping up.
Why do dogs jump up? A plausible explanation arises from their ways of communicating with each other. A puppy greeting an adult dog often licks the adult’s muzzle -- a polite, deferential behavior. Dogs, of course, descend from wolves, among whom muzzle-licking is how pups get the grownups to regurgitate food for them. Domestic dogs rarely nourish puppies this way, but muzzle-licking has survived, maybe because deferential behaviors are handy for a social animal. Think of humans saying “No, after you.” Muzzle-licking is also an appeasement behavior -- something you trot out to de-escalate a fight. A human might lift up his hands, palms toward the person he’s arguing with.