Open the 
Sent BizTalk Purch.
Document window.
Click Document, List to see a list of all sent BizTalk sales documents.
Find the relevant BizTalk purchase document. You can identify the document by looking at the No. field.
Click Functions, Resend.
Once you have sent a BizTalk purchase document, you might want to resend it. You can do so from the different sent tables.
To resend a BizTalk purchase document (unaltered), follow this procedure:
Open the Sent BizTalk Purch.
Document window.
Click Document, List to see a list of all sent BizTalk sales documents.
Find the relevant BizTalk purchase document. You can identify the document by looking at the No. field.
Click Functions, Resend.
If you want to change a BizTalk purchase document before resending it, you must copy the original BizTalk purchase document, make the necessary changes and send the document as a new BizTalk purchase document.