Try different foreplay and sex positions, make her feel wanted, whisper things in her ears etc.. Usually this helps alot, using the same technique can be like watching the same movie over and over again, best of luck to you!!
It's probably hormonal to some extent, and familiarity will play in also (making sex less suspenseful and therefore less exciting), just buy some lube and use it. Don't worry, at least she still wants to have sex with you.
Hi,
You really can't measure how pleasurable an orgasm or sex is for a woman, by how wet she becomes. Dryness can happen from time to time; it's not something that can be switched on and off. Sometimes female orgasms can be more dry than other times, especially in more mature females, due to fluctuations in hormone levels. Dryness can also be common for women who use birth control or medications, but that doesn't necessarily mean dryness is a problem...
It's normal for women to experience individualistic orgasms; in other words, no two orgasms are the same or have the same results. If your wife is still achieving orgasms during intimacy with you, I don't think you have too much to be concerned about at this point. Twenty seven years of marriage is impressive, and I doubt that she has lost interest in you since you still have an active sex life.
You could always ask her, if she would like to try something new to spice up your repertoire. Or ask her about what ideas she might have that could help enhance your sex life ~ you never know, she just might surprise you.
Best of Luck