Price Update in PO

Hi My company requirement is to Update PO net price if PIR net Prices Changes i understand that PO price can not be changed if GR has been done . we are only trying to Update Those POs whose GR has not been done yet .there is a Price update Button under condition tab that will update PO net price from PIR

manualy now if we have whole bunch of POs is there any way we can automate this process , is there a FM or user exit that will do that ,i can not use BDC as it is not reccomonded, I am very new in SAP please help

                                       Thanks in advance