About excess itr received

The return can be revised  before the expiry of 1 year from the end of the Relevant Assessment Year or before the completion of assessment (whichever is earlier). Refer:  https://www.charteredclub.com/revised-return/

But how to pay the excess amount to the govt. If through challan 280 then will it be regular assessment tax? If yes then can i file regular assessment tax without any demand notice?

Yes, It will be self assessment tax, and any such additional income declaration can be incorporated in revised return.

Thanks A lot for the help