Urgent query of service tax

Dear All,

Pls suggest,

I have raised and issued invoice to the party of Rs.1Lac plus service tax dtd 15/03/2012, But due to some reason Invoice was revised and reissued to the party of Rs.1.75 Lacs plus services

but in this case i forgot to pay service tax on 30th March 2012 on extra amount of Rs.75000/-, I have paid on previous invoice amount of Rs.1Lac

Now what should I do ???