If it's not broken, don't fix it.
When it comes to sex, your greatest fear should be boredom. You cannot expect to keep doing the same routine and have her erupt into applause after a performance she's already seen three times that very week.
We know, women are like trigonometry, and you're tempted to leave all of the variables in place once you've cracked the elusive formula that brings her to orgasm. But, be warned, if you're recycling the same plays you've used since you first met, your sex life is in need of a serious fix. Instead of obsessing over "what works," explore new routes to reaching the finish line. Even if it leads to a dead end, your sex life will undoubtedly be better for the discovery process.