My lifesaver was the book "Healthy Sleep Habits, Happy Child," by Dr. Marc Weissbluth. I've used and reused it with my 7 kids. It covers every sleep issue you could ever encounter, and it has always worked for me. I would definitely NOT give up the nap, but I would try to keep it fairly early. I had the best luck with putting my kids down around 1pm. Then they went to bed at 7pm, probably until they were at least 6 years old. If he can't get back into the bed himself, try just putting the mattress on the floor. That way you won't have to lift him in, and he's close enough to the floor to be safe if he rolls off. The book will walk you through, step by step, the whole process of teaching him to settle down, stay in bed, and go to sleep. A worthwhile investment, especially with another little one coming. Good luck.