If you don't see Make recurring in the footer of the Bill, then I recommend clearing the cache of the web browser you're using for your QuickBooks Online. This is the best way to handle missing buttons in QuickBooks Online because these files can become outdated, causing issues like the one with your Make recurring button missing from your Bills. I've provided a link to help you with the process: Clear Web Browser History.
Once finished, then create or open a Bill and see if the button appears in the footer. If not, here's another way to set up a Recurring Transaction:
Go to the Gear icon at the top-right of the page, then select Recurring Transactions.
Press on the New button at the top-right of the list.
Enter all the necessary information.
Hit the Save template button.
If you have further questions or concerns, just know that I'm just a hop, skip, and a jump away! Have a beautiful day.