Remote code update

Ahh ok. Personally I'd say rewriting the main flash would be a bad idea - if there were a problem, you could brick everything.

Maybe:

• Turn on 'Save on Send' in the IDE - this'll save the JS code to flash as text (rather than saving an image of RAM to flash).
  
• Put all of your V1 code (if possible) inside a function, so that you then call that function to initialise everything and you're sorted.
  
• Call that function in the fallback of the bootloader
  
  

That way, your V1 code isn't taking up any RAM at all until it's called - so you don't even need to unload it.