inclusive Excise duty after GST

No Need to reduce/increase the basic price. 

Just replace excise and VAT with GST. 

excise duty was given as inclusive. so is it require to unload from offered price?

you need to overlaod. 

GST Council tried its best so that final tax rates are revenue neutral. In most of the cases GST rates are combination of VAT +:Excise Duty or Service Tax. So in your case you replace Excise/ VAT with GST.
Also if he charges rates inclusive of excise plus GST anti profiteering provisions are applicable and same is bared under GST Act.