Show Reorder icon in your customer order detail page needs to insert the below code in customers/order.liquid file.
Customers/order.liquid file path: Login into Admin panel-> left side menu select Online store -> select Themes.
Now left sidebar load with file list. Check at Templates bottom of the list “customers/order.liquid” file, click on it.
Insert below code where you want to show the Reorder icon at this position in the file and save it.
<div data-id="{{order.id}}" class="identixweb_advance_reorder"></div>