Couples get tired of routines even when it comes to making love. If you feel that there are some issues about the level of desire, try to implement something new.
There are wonderful sex ad videos and books. Also, ask her if she would feel comfortable in using sex toys (many women do) The key is to find out what she likes and how she likes it done.
You level of desire may be as a result of different things. Some things affecting libido are lower levels of testosterone and depression. It can also be as a result of having your interest worn out if you pretty much expect the same thing.
It may be helpful to at lest see if she would like to dress up in different lingerie and to have fore play.
Other things men have tried is hypnosis.
There is not one specific technique that works on everyone. The key is to find out the reason behind your most recent change in behavior and address that.