ignoring is a very hard thing to do. he is trying to get a reaction and he got it. ofcourse you shouldn't accept the harder biting. but he now has found a way to get the attention he wanted. what i'd suggest is keep ignoring him and leave the room. don't let your pup follow. wait a minute and return. if he starts again leave again. this does take time but by shoving toys in his mouth your giving him what he want! smart those dogs are!