There is nothing wrong in claiming refund through payment of IGST on future exports, provided the ITC was otherwise eligible as per law. Earlier rejection of ITC refund claim has nothing to do with this. For procedure to be followed, pl go through Sn.54(1) of CGSTA'17 r/w Rule 96 of CGSTR'17 r/w Circular No.125/44/2019-GST dt. 18.11.2019. Relevant para from the circular is extracted below:
Refund of Integrated Tax paid on Exports
Refund of Integrated Tax paid on Exports
58. The refund of Integrated tax paid on goods exported out of India is governed by rule 96 of the CGST Rules. The shipping bill filed by an exporter is deemed to be an application for refund in such cases, but the same is deemed to have been filed only when the export manifest or export report is filed and the applicant has filed the return in FORM GSTR-3B for the relevant period duly indicating the integrated tax paid on goods exported in Table 3.1(b) of FORM-GSTR-3B. In addition, the exporter is expected to furnish the details of the exported goods in Table 6A of FORM GSTR-1 of the relevant period. Only where the common portal is able to validate the consistency of the details so entered by the applicant, the relevant information regarding the refund claim is forwarded to Customs Systems. Upon receipt of the information from the common portal regarding furnishing of these details, the Customs Systems processes the claim for refund and an amount equal to the Integrated tax paid in respect of such export is electronically credited to the bank account of the applicant.