Having item_template reload function is kinda useless, when item data is loaded into the memory. Either way, a restart is still needed to fully update the items, or items will bug out during run time.
On one of my projects, I've managed to what you want to do, but it came with a big down side. Sometimes it can make the server very unstable, and that's something you really don't want to have. It's best to just make a restart when new data is added to the server.
Also, do you're development on your local machine, and add new content when you're ready to do so. Do development on live server, with drive the population away.
Anyways, good luck on your addition to your server.
Thank you, and i success with the script it works great