Revised return 17-18

Note that We already submitted GSTR1 (Sep,2018) return dated 18/10/2018 . but  some Export Invoice No,, Port Code No , Shipping Bill No. want to change (or IGST refund purpose)  the F.Y. 2017-18. can we REVISED 17-18  return  when we will submitted GSTR1 (OCT, 2018) RETURN. because We have heard that  31/10/2018 is last date for REVISED RETURN for F.Y. 17-18 & 17-18 is closed .Please solve this problem ...........