GSTIN number remains active until you file final return with in 3 month from cancellation or the date of order of cancellation whichever is later(Section:45 Of GST Act 2017).
You can file return with same GSTIN .Your GSTIN will get revived.If you got order of cancellation then you can file revocation.
Revocation can be done within 30 days from the date of serve of cancellation order.(Section: 30)