The flavor that you taste in gum is usually made from sugars or artificial sweeteners of some kind. As you chew the gum, the sweeteners mix with your saliva, which breaks them down and sends them down your throat when you swallow. After chewing for an extended period of time, the gum is bound to lose its flavor. If you like the feeling of having the gum in your mouth but want the flavor back, you have a few options. You can also try a few tricks to prevent the flavor from leaving the gum in the first place.
Dip a teaspoon into some sugar and get an even spoonful. Then, put the sugar in your mouth with the gum. As you chew, the sugar will mix with saliva and the gum and reintroduce some of the chewing gum flavor.
Add a new piece. If you want to get the original flavor back of the gum, you can simply add a new piece. Once the two pieces of gum mix together, the flavor might actually be stronger.
Chew slowly. The more slowly you chew the gum, the less flavor you will lose.
Avoid swallowing saliva for as long as possible. When you swallow saliva, you swallow some of the flavor of your gum away.