Hi Rohit,
I think in this case the SC will have the status I1115 (Follow on Document deleted) once the PO has been deleted. Then upon logging into the portal for this SC think there would be an option to order again to allow us to create the new corresponding PO document.
Additionally we can use the FM BBP_REQREQ_RESUBMIT to create the new PO for the SC.
Thanks & Regards
Pramod