Excise Rate Increase during Miro

Dear Team,

I Have an issue while doing MIRO.

The Problem is we have created PO with excise 10 % and posted MIGO as well as Excise invoice also.But Later Excise % Got increased from 10 to 12.

Due to this My MIRO Value is getting changed,but if i want to reverse MIGO it is not possible because the quantity got consumed fully.

in this case,i need Your valuable suggestion on how can i go with Posting MIRO??? Please Guide..

Thanks In Advance.

Vinai