When I first started having sex I was able to have vaginal orgasms very easily. As I've gotten older, manual clitoral stimulation has become necessary about 99.9% of the time to reach climax. Is this normal and is there anyway to make vaginal orgasm easier again?
First of all, let me say that this is totally normal. As we age, our bodies change in many ways and sexual changes are extremely common. You can either fight the change and hope that things go back to the way they were before, or you can accept it and learn new and fun things to try, which it sounds like you're already doing.
That said, vaginal orgasms and sensitivity can be worked on. You can try using kegel exerciser balls such as the Ami, Luna Balls, or Crystal Egg to tighten your PC muscles, which are a key part of vaginal orgasms. Tightening this area can increase sensitivity and pressure on the G-spot. Sometimes, just the clenching and releasing of these muscles can bring a person to orgasm (or at least close), so strengthening them will retrain and prepare your body for a more internal orgasm.
Another option is to use toys and clitoral stimulation BEFORE you have vaginal play. Get yourself close to orgasm without spilling over, then continue with vaginal stimulation. This can increase vaginal sensitivity as well, making it more likely that you will cum. Using your hand, a partner, or a vibrator will draw blood to the whole area, raising arousal and lowering the orgasmic threshold.
I hope this helps! Good luck with your vaginal pursuits!