How we can change order type on booked sales order/lines

Hi Friends,

There are 100+ booked orders which need to change order type.

We are using some custom attributes in lines for business requirement so Can't copy and create new sales order as these custom attributes will be not copied.

again entering custom attribute very difficult as there are many attributes for each line.

So is there anyway to change order type on booked sales orders ?

Thanks

Laksh