In case anybody stumbles upon this question who cannot reload their webserver (long running console command like a queue runner) or needs to reload their .env file mid-request, i found a way to properly reload .env variables in laravel 5.
use Dotenv;
use InvalidArgumentException;
try {
Dotenv::makeMutable();
Dotenv::load(app()->environmentPath(), app()->environmentFile());
Dotenv::makeImmutable();
} catch (InvalidArgumentException $e) {
//
}