How do I make changes to my firmware?

I have a DaVinci 1.0a that has been flashed with Repeteir 0.92.10. I need to make some changes to the Configuration h file. I can open the Arduino software and see the Configuration h, make the changes and check them. They check fine and I click upload, it goes through the files then fails to upload. Times out after several tries.

My Baud Rate is set at 115200 and I am able to connect with Repeteir Host.

Do I need to jumper the pins on the motherboard to make changes to the Configuration h?

Suggestions why I am unable to upload to the printer?