Modify My Android App With Firebase

I need the my android app modified. Currently it takes orders and sends them off to api but then it is supposed to save these orders in firebase, it also saves them locally, but 15-20% of these orders are not getting saved to firebase. So we need to add in a function that every 30 minutes it takes the orders saved locally and checks by order id if they are in firebase, if they are then it does not add them but if one or more is missing then it adds those.