How to get a customer to pay after not completing

I have had a order today but the client has not completed payment. They selected PayPal Express and the order has gone to OPEN. Now the client wishes to pay but I can not find a way to do this on the client side, only from order management which is no good for the client.

Is there a way to reset or turn on a button that says order unpaid click here to pay like to does for a failed payment.

Also I found that if a payment fails 3 times the client loses the button to pay again, any ideas why this happens?

Go into “Order Statuses” under “Open” status make sure that “Pay order again” is checked.