Xamarin Application to upgrade

I have existing app in Xamrarin with full source code it was built in 2 ur old version so now need to be upgraded. Later after test i need it to be published in Android and Iphone Store. (Note : i would need apk or files which we can upload on app store. we won't be able to give you details of both the store.) i would need small changes for 2-3 hr like moving text box or changing variable value.