There is no "normal" way to do it. What you can do, however, is to always provide a link to your app in Google Play and have an intent in your app handle that link. Thus, the app will open when the market link is clicked if it has already been installed. The downside is if the app is installed, the user will be presented with a dialog and will have to make a choice of whether to launch the link in a browser or in your app.
See this answer for a code sample: https://stackoverflow.com/a/12901352/379245