So you have uploaded your app to Google Play and made it available for the whole world to see. But what do you do if you realize that the app has a bug that has to be fixed?
1. Fix the bug in Construct 2 (or do any other change to your app for that matter), increment the version number and export (to the same folder as you have used in earlier exports).
2. Open Intel XDK.
3. Click the Projects tab (and if necessary open the corresponding project).
4. Open the Build Settings menu
5. Increment the fields App Version and App Version Code.
6. Build the app and download the APK file received.
7. Open Google Play developer console and then the app you want to update.
8. Go to the APK menu and click Upload new APK to Production and select the new file.
Hopefully that should do the trick. You might not actually need to update the file version inside Construct 2, but I just find it easier if version number is the same both in Construct 2 and Intel XDK. The version code can be incremented like 1 -> 2 -> 3 etc, but how you do the numbering is obviously up to you.