[Marilize]

He's just a puppy and doing what puppies do. They simply can't be expected to the potty trained at 15 weeks. Yes, you need to start again, but it's not as hard as you think and you don't have to do every two hours.

What I did to potty train all my dogs (and I'm currently potty training my litter of 8 week old puppies in the same way), is to make going outside fun, exciting and a group outing. I have certain words that I use to let them know that we're going outside, so that by the time I reach the door, the dogs are very keen to go out.

Once outside, I wait for them to potty and in the beginning, I would say "potty" just before he/she finished peeing. You don't want to say it too early or they will stop. Now I just say potty and they will each go to find a good spot to potty. They get loads of praise, sometimes treats and play time, afterwards.

Rinse and repeat until they truly understand what you want.

This has been the most successful way that I've found to potty train my dogs and it took the litter of puppies less than a week to catch on. They will still make mistakes inside, but you just clean those up without a word with a vinegar/water mixture to remove any smell. Make a big fuss about going outside and they will come to expect and look forward to it.

Just one more note on dog training - the best thing you can do for your puppy is to develop your own language of words that he understands. I don't mean commands like sit or lie down, but rather words that let them know what's going to happen next. I have a wide array of these like "Hungry?", "Let's go outside", "Pee-pee", "Wanna drive", "Give me a kiss", "Watch out", etc. and my dogs respond very well to them. The more you use words like these that they understand, the more rewarding your relationship becomes.