Gstr -3b wrong filled and how to pay correct gst

We are  filled  Wrong GSTR -3B for July'17 -----

Example : As per Filed  GSTR -3B GST Liabilities was Rs. 50,000/-  and  In GST Liabilities Register Showing Rs. 50000/-

----- But Actual GST Liabilities is Rs. 100000/-.

Question: How to pay Actual GST Liabilities of Rs. 100000/- ------Whereas Liabilities Register Showing Rs. 50000/-

Please suggest Step By Step so that we can pay actual GST Rs. 100000/- instead of Rs.50000/- for avoiding GST Liablities Register

Best regards