Using WooCommerce Order Again button
You'll need a copy of WooCommerce Order Again button to proceed with this guide. You can get the plugin here.
Once you have activated the plugin WooCommerce will show an 'order again' button in the customers order history. If you have (test) orders in your own account simply navigate to My Account > Orders and look behind each order to find the Order Again button.
Clicking this button will put the same items from the previous order in the shopping cart so the customer can buy them again.
The plugin has no settings.