I am quite new to PayPal rest API and wanted to provide user with a way to retry payment option in case user does not continue or cancel from the PayPal approve URL. Should I create a new order altogether and get a new approve URL or is there a way to retry payment for an old order in 'CREATED' OR 'APPROVED' state?
An order is valid for 72 hours from the moment it is created, and for 3 hours once loaded in a PayPal checkout for approval.
If a user abandons it and is going to restart their checkout on your site, it's generally best to forget about the old order and generate a new one. You can specify a unique invoice_id for orders to prevent any accidental duplicate payments (by default the PayPal account will only allow one completed payment per invoice ID)
Rather than redirecting away from your website to PayPal for approval, for modern websites it's best to keep the user on your site, and have them approve the payment in an in-context experience/lightbox, which also has the option of expanding a credit card form right within your website. See the demo at https://developer.paypal.com/demo/checkout/#/pattern/server