The production of Semen is generally constant. But the reserves build up and when you masturbate, you release it from the body. If you do not masturbate, then it has its own self release in the form of wet dreams.
An increase in seminal fluid has many benefits. First, it is pretty awesome when you can unload a large amount of seminal fluid on or in your partner. Second, it leads to a more intense orgasm. The reason is simple. When you increase your seminal fluid, it takes longer to ejaculate. When you have a longer ejaculation, you will have a longer orgasm.
One of the ways to increase the semen flow, is to learn to walk the edge. Edging - also known as surfing, the stop-start method, or peaking - occurs when you prevent yourself from ejaculating. Basically, when you feel that you are almost at your climax, you work to calm yourself down and then continue. Not only does edging encourage your body to increase seminal fluid, it will also extend your time in the bedroom - a noteworthy side benefit.
There are also exercises that will help. These are commonly known as Kegels, and they involve exercising your pubococcygeus (PC) muscles. To locate these muscles, stop urinating mid-stream the next time you use the bathroom. The muscles you use to halt urination are your PC muscles. You can work these muscles out every time you use the restroom. Once you have located them, you can really practice any time or anywhere. Your goal should be able to flex these muscles for several minutes at a time.
By increasing the strength of your PC muscles and through edging, not only will you increase seminal fluids, prolong your time in bed, and have a more intense orgasm; but edging and stronger PC muscles also allows for a more forceful ejaculation.
Your Diet also helps to increase the semen content.
There are a couple of basic building blocks that you need to focus on to increase seminal fluid:
1. Zinc and Protein. The good news is that most sources of zinc also include protein. Your best food for zinc will be oysters. They actually contain over 10 times the amount of zinc than the next best alternative (beef) does. However, beef, chicken, seeds, and nuts are all good sources of zinc and protein.
2. Water. Increase your seminal fluid by increasing your water intake. Try to drink at least eight cups of water every day. While other fluids can help keep you hydrated (think sports drinks), it is important that you don't consume too much caffeine or alcohol. Both of these serve as diuretics that will actually encourage your body to expel water. You should also look at increasing your consumption of foods that have a high water content. These foods generally consist of fresh fruits and vegetables.
In short, just relax and enjoy your wet dreams.