Let visual studio recognize head file of module?

I download the source code of UE4, and play with the sample ,but after I add some module in the build.cs, the visual studio can’t recognize the head file of the module I add ,even though the program compile fine and can run with the new module I just added.

Is there some kind of refresh button/way that can let visual studio recognize the the module I just added so that intelsense can work on it?