RE: Bulk update Existing sales order Line (Item Price) after Price Change
                     
                    
                      
                        Hy Amith,
as far as I know there is no out of the box solution for this.
If the number of sales order lines is no as large (< 1.000) you could use the Excel Addin. This could be a individual designed Excel template that contains only the columns you need to change.
For larger recordsets I would create a Data Management Project with the needed entity (sales oder lines V2),include as less columns as needed, export, recalculate in Excel and import again. 
If this is an always recurring process you should think abaout customization as "Mass sales order lines update", like it is available for item master data in Retail and Commerce (Mass update worksheet).