how to use increment function in laravel

i am using DB to store values in database.

i have "course fees" column i what to "increment" the "course_fees" value in column.

for example

 DB::table('student')->where('registration_id','=', $request->registration_id)->increment(['course_fees' =>$request->course_fees]);

this code increment the inserted value

how can i modified below code for increment "course_fees" value like above

      DB::table('student')->where('registration_id','=', $request->registration_id)->update(['payment_date' => $request->payment_date,'balance_fees' => $request->balance_fees,'course_fees' =>$request->course_fees]);

via Chebli Mohamed