Hi therePC2018,
Thank you for your post and welcome to the community!
In general, you can get up to 12 refunds per person, per year under the PayPal Return Shipping on Us service. Only one refund is allowed per PayPal transaction ID. To make sure you know how many refunds you have done until now, you best option would be to consult the FAQswhere you will be able to find the information on how to contact the relevant team in charge of this service. They will be able to specify how many times you have already used this option!
Hope this helps!
Martina