I don't think that what you are doing is very nice to your DH. He has adjusted to you not wanting more children. Springing it on him that you've changed your mind isn't fair. What happens if he doesn't want more children? What happens if he has started to plan a baby-free life and you start nagging about babies again? "Convincing", to most men, means "nagging until he gives in or walks out" - and many don't really want to walk out on their families.
I just know that my DH has changed his mind a few times (claims that he has never done that too) and the emotional turmoil I've been in from it. And it isn't fair. If you agree to something with your OH, you should stick to it. At least then people know where they stand, rather than living on the edge the whole time.
Bookmarks