I have given my exam papers, I can sometimes give my exams again for improvement. But for tax returns, I do so only for correcting any errors I find.
Once I file a tax return, and later I discover that I made some inadvertent mistake in my tax return, I can file a revised one and correct that mistake. I can revise my return more than once.
My first filed return is called my Original Return, and any further returns filed are called Revised Returns.
But again, the last date of filing revised return is again 31 March of the year following. It doesn’t change.