How can I make kissing more enjoyable?

Every guy I've ever dated I only enjoy the kissing for the first month or so that we're dating. By enjoy I mean I get sexual pleasure out of it and it's not boring. Because it happens with every guy I'm sure it's me and not the guys. I've been with my fiance for almost 2 years now and as expected, the same thing happened with him. We're going to be parents soon and so I've been trying to find ways to spice up our sex life until then so we can make the most of the time we have left to have sex whenever. It's not that he's a bad kisser and he seems to really enjoy it when we kiss I just wonder why it seems so boring to me. Making out seems almost like a chore to me. Any suggestions?