babel-plugin-espower | Babel plugin for power-assert

I'm using a babel plugin to load environment variables from a .env file into a React Native project, but changes to the .env file are not loaded until the javascript file importing them changes. I'd like a way to tell the react-native packager to recompile in the event that this file changes. I would accept an answer that:

1. Simply re-transpiles the entire project when a specific file (.env) changes.
2. Re-transpiles only those files containing a specific string, say foo

Is there a simple way to do this by writing a plugin/middleware? Maybe a separate background script that fires events to watchman that the react-native packager is listening for?

[EDIT in reply to a comment]

My current .babelrc is the following, where babel-plugin-react-native-config is a plugin I wrote to do hot variable swapping in conjunction with the react-native-config package.