Finale is a great tool at helping you maintain your FBA stock levels by leveraging the reorder function.
Step 1: Establish the desired stock levels for your FBA location using the reorder points. How do I set reorder points per location for my products?
Step 2: Run the "Reorder for each product and location" report. Be sure to filter it by location (Amazon), and (optional) Reorder Variance which is the amount recommended to send to FBA based on your established reorder points (greater than or equal to 0, less than 0).