The shipment plan can be cancelled at any point of time in Step 2 , 3 and 4. Once cancelled, all the box data will be lost and you should be able to redo the shipments from Step 1.
Follow the steps below to cancel the shipmen plan.
Select the batch for which you want to cancel the shipment plan and redo the shipment.
Click on the "Cancel Shipment Plan" Button on batch items page as shown in the screenshot below.
This should cancel the existing shipment plan of the batch and you should be able to redo the shipment.
Pls Note: Cancelling the shipment plan will loose all the boxes/packing of the previous shipments and you will have to create the new shipment plans again.