Have you gotten a little tired with the same positions that you have been using for years. In the beginning of a relationship couples will try lots of different positions. usually after times goes on they will get tires and bored and use only one or two positions. The biggest problem is after a period of time in the relationship you get used to the those same one or two positions and the love making get shorter and shorter.
The first thing you should do is try to enhance the current positions yo are using. A good example is if you are using the standard missionary position try to raise your hips and you will get a more direct thrusting action. You will see just by making a little adjustment can make a big difference when making love. You will find that both of you will become more aroused and that the climax will be longer and more intense that it was before.
The most important thing to do is to experiment with different positions and adjust them to what feels good to you. Some people like the missionary position the best, they feel it give the man and women the best thrusting action. Other people, especially men, like to use the doggy style position because it is a way for them to have maximum penetration and also they can see what is going on.