can I refund my rover payment from paypal to my rover profile?

Is there some reason you cannot access that old Paypal account? If you can, then the easiest thing to do is log into that old account and send the funds to your new Paypal account, where you can withdraw to a bank account or whatever you usually do.

Refund back to Rover, probably not. I would suggest you contact Rover support and also PayPal support