The easiest way may be to create a -prj directory for each QVW and then the document layout will be automatically exported every time the document is saved. I don't recommend doing this with production QVWs though.
You can write a VbScript using the QV automation API. Open each document in turn and call ExportDocumentLayout on the doc object.
Can you please provide me the VbScript for ExportDocumentLayout of QVW as am not aware of vbscript. Should i run the vbscript in Load Script of each document ? Will it be able export all the sheet objects of QVW at a time by writing script?
And also can you provide the exact URL for QV automation API