Installing your application to a physical device is fairly simple. In fact, aside from setting up the device to allow non-Market applications and to allow debugging, installing your app on a physical device requires virtually the same steps as installing it on an emulator.
Well, the same goes for reinstalling your application. When you change or update your app, you need to reinstall it to test it again. Luckily, Android makes doing so pretty easy. You don't have to do anything special to reinstall your application. Just perform the same steps you used to install the application the first time: Choose RunRun or press Ctrl+F11. (Easy, huh?)