You might want to detect disconnect and try and automatically reconnect?
You can now add images 'in-line' as ascii with http://www.espruino.com/Graphics#images-bitmaps. What you've done is fine but having images as text makes them much easier to tweak if you need to later on.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Actually, some other thoughts: