Well, PLUS loans are the most deadly. They have no federal protections (such as deferment, or income based repayment) and they have the highest rates! So I don’t blame you for wanting to refi. There are two ways to do it — either refi the loan into the student’s name (if he or she has a good job and good credit) or just refi in your name.
I typically recommend www.SoFi.com — the site that pioneered this concept. But first you might want to use this comparison tool at www.Nerdwallet.com. Here’s a direct link to the page. It not only has links to multiple refinancing options, but explains the process clearly. You’ll be amazed at how much money you’ll save on interst!