Can LUT be filed now for FY2018-19 now

Hi Members,

One of my Client is into export of services. 

They have not filed the LUT for FY2017-18 and FY2018-19 but had export of services without payment of GST.

I have following queries in this regard -

1. Can LUT for FY2017-18 and FY2018-19 be filed now as export has been made without payment of GST?

2. Can the department ask the client to pay GST on the export done without payment of GST ?

3. ITC on purchases made during the year will be refunded ?

Thanks in advance for your advice.

Amit