Step 1: Terminate the running web server
Step 2: Modify the .env directive CACHE_DRIVER to be array instead of file.
Step 3: Remove the cached bootstrap files by running php artisan optimize:clear
Step 4: Flush the application cache for good measure by running php artisan optimize:clear
Step 5: Run php artisan serve. Any real-time changes to your .env file should reflect immediately on the app rather than having to force a web server restart each time.