Sync offline android sqlite database with remote database

So I have developed an android application which allows for the creations of loans and returns. Currently the app works by maintaining an internet connection and automatically synchronises created data between the app and the remote database, using AsyncTask.

What I want to do is be able to save this data to a SQLite database and later synchronise the data to the remote database by pressing a button. This will enable my app to work even without an internet connection.

Is there anyway for me to do this? I have followed tutorials on androidhive and programmer guru, neither of which have been successful.

Ideally it would work without a REST/SOAP service as I am unsure how to implement these (I am still a bit of a novice when it comes to programming!)