N the month of August the application form will be available on cbse official website which you have to fill online then it will ask in which you subject you want to apply for improvement…you can select all subjects and additional subjects also then you have to pay the amount for improvement exam which you have to pay at bank. take the print out of the acknowledgement and the e-challan and deposit the fees at bank… you also have to change your region when you type the pin code then according to that you will get your centre as well as new region means you region will change. it don’t effect anything. after all these thing you have to send a xerox copy of your marksheet e-challan acknowledgement to the regional office which you get. the address will be returned on the acknowledgement after that you have to wait to get your admit card which you will get online on month of February…and improvement marksheet will be send to you address which you fill at time of applications form filling time. if you get less marks in improvement then old marksheet will be valid.