Gstr1 lut export invoice wrong rate

I entered all GST export invoices under LUT under 0% erronously for 2017-18. It should have been under 18%. Can I amend the export invoices now? If yes, what should the revised invoice number be? The original invoice number will do in place of the revised invoice number?

I haven't yet applied for refund for any of the months in 2017-18. Will revision create any issues in refund? Will it be alright if I apply for refund under the current status with all bills under 0% without amending the invoices because there are more than a 1000 invoices for 2017-18? Thanks in advance