- Run 
phonegap build androidfrom the folder containingwwwfolder cdto this pathplatforms/android/- Make sure 
ant.propertiesin this folder contains these keys and the right values 
key.store=
key.alias=
key.store.password=
key.alias.password=
- increment the 
versionCodeinAndroidManifest.xmlin this folder cdtoant-buildfolder from this folder- run 
./build --releasein this folder. 
Now you have a bunch of .apk files in this folder. The one with the name <Project_Name>-release.apk is what you can upload to Google play.
References: