Refund of IGST paid on imports

dear experts,

can anyone solve my question..?

I have imported some goods @ $ 100
ie ₹ 7000 (exchange rate is 70)
assessable value for custom is $ 400
i.e ₹ 28000 (₹70 * $ 400)
custom duty paid @ 10 % is ₹ 2800
IGST paid @ 18 % ₹ 5040

will sale this goods locally @ ₹ 14000
GST @ 18 % will be ₹ 2520

output liability. ₹ 2520
input ITC (IGST) ₹ 5040
net ITC balance ₹ 2520

now how can I take refund of this ₹2520.