Yes, ignore him. Instead of touching him or picking him up when you first get home, just ignore him. Take the pressure off. When they still do it as an adult, there's some fear. so keep a list of the circumstances behind when he does it. Then avoid those triggers. He may seem like there's no fear (happy and wiggly) but there's something causing him to tell you that he's no threat (Submissive peeing is just that, a signal to other dogs that "I'm just a puppy, I'm no threat!!!") So when an adult dog does this, it's due to feeling threatened.
Maybe all you need to do is not look him in the eye, or not lean over him, or let him climb on you.
Oliver is a very nervous dog, and for a long time, if I grabbed him wrong he'd pee. I just ignored it. I began de-sensitizing him to being grabbed, by teaching him to jump into my arms as a trick. It worked wonders, and he hasn't peed all over me for more than a year now. I also never touch him when he's feeling uncertain, I let him choose what he wants. I dont want him scared, so if he's not sure, I let him off the hook.