Sometimes the PayPal redirect just doesn't go through and we are left with an uncompleted order and no easy way for the customer to complete the order without doing a completely new order.
How about, on the back-end, having a 'Complete PayPal Payment' email which would RESEND the order through to the person?
(or an automatic email sent by the system)
The person would then click a link in the email to submit/complete the order with PayPal again.
I think that you can eventually use the
Payment of orders not paid immediately option that will enable your customer to finalize their order if they didn't completed it via the listing of the orders of the user.
Note that this feature is only available through commercial versions of Hikashop.