You can add a TCP based REPL to any LambdaNative app by inclusion of a single module. This allows you to connect through emacs and run/alter code on the live system, potentially directly on the mobile device (although it would make more sense to do this sort of iterative development on a build for the localhost). The setup is described here:

https://github.com/part-cw/lambdanative/wiki/Using-Emacs