I installed step by step from https://www.npmjs.com/package/laravel-elixir-livereload but it doesn't work.
npm install --save-dev laravel-elixir-livereload
Next, I added it to my Elixir-enhanced Gulpfile, like:
var elixir = require('laravel-elixir');
require('laravel-elixir-livereload');
elixir(function(mix) {
mix.livereload();
});