You can run the process in a screen which will allow you to disconnect and reconnect without interrupting the process.
- SSH into instance
- Type 'screen'
- Run script
- Ctrl+a Ctrl+d to detach
You can now disconnect.
Reattach to the screen by typing 'screen -r'
You can have multiple screens and you can simply attach to this using the PID
For more information on screen, check out their screen manual: CLICK HERE