I assume that you are using Paypal because you don't have/want to deal with the "full stack" required for credit card processing (i.e. bank account, merchant account, payment gateway, etc.). If this is the case and you want similar convenience for processing recurring payments, I would take a look at Saasy or Stripe. They provide a full service and, from all accounts, are easier to integrate and more reliable than PayPal for recurring billing scenarios. I have experience with Saasy and have been very happy with it to date.
There are pros and cons to each, or course.
Saasy is a product from FastSpring and is well established, works with companies pretty much anywhere in the world and has great support for developers but takes a fairly large chunk of the sale (around 9%). Stripe is newer, so less proven, and only works with companies in the US at the moment, but takes a smaller cut of sales (around 3%).