Not to be boring, but things that promote healthy orgasm & ejaculation are the kinds of things that generally improve health. Maintaining healthy blood circulation through exercise, eating energizing & nourishing foods, getting enough sleep, not smoking -- all of these things will help you to experience satisfying orgasms and *may* effect semen output. If you are ejaculating often -- through masturbating very regularly or having regular sex -- ejaculating less often may also mean ejaculating more when you do.
That being said, the amount of ejaculate someone produces isn't usually an indicator of health, sexual performance, etc. (unless you suddenly see a drastic reduction in your production; in this case, check in with a doctor to make sure everything is functioning alright). So I guess my question would be, why is this a concern you have?