If you disconnected the device that converts the USB interface (16U2 or CH340 or whatever) to the serial interface on pins zero and one of the 328,it must make downloading new code to the 328 difficult.
I'd be inclined to drop the BT serial rate to 9600 (or lower), and put it on a software serial connection, and leave the hardware serial connection for debugging.
Don't forget to reconnect the USB/serial converter
Ok ,
But i have a doubt That after connecting USB for uploading .
And after uploading i have to disconnect USB as it is controlled by bluetooth.
So i have to disconnect USB ?