Yes...There are several ways to re-enter a PA if you fall out or roll (turtle) it. You'll have to practice a couple different techniques until you find one that works best for the particular situation so you can avoid a panic if/when it happens. If you're like me and carry alot of equipment stored behind the seat when you go fishing...After a turtle or after falling out, a re-entry from the stern would be impossible. A side re-entry would be the way to go provided you don't have the side rails covered with equipment. The more accessories you have mounted on the side rails and/or side boards, the more challenging re-entry becomes
...There are a few ways to get the PA back upright, but if your PA is loaded with gear, heavy, and you haven't lost everything to Davy Jone's locker, it would be easier to use ropes that you previously attached to each side rail before the fishing trip (6-8ft. length) that you can now grab from the opposite side of the hull from you. Throw one end over the hull, swim back around to the other side, and while placing your feet against the hull closest to you, try to stand up while pulling back toward you with the rope. Your body weight should be enough to flip the PA back upright. If it is windy, use the wind to help you flip the PA back over, by facing the wind while pulling the rope back toward you.Then, once the PA is back upright, in a quick motion you want to swim kick, while holding the side rail closest to you and try to pull yourself over the side rail enough to grab for the side rail on the opposite side of the PA. Then pull yourself the rest of the way onto the PA. Thats just one technique 
...Check out these links to see other techniques you could use. https://www.youtube.com/watch?v=19pQMZI ... re=related
https://www.youtube.com/watch?NR=1&feat ... hG4f9mMNCs
https://www.youtube.com/watch?v=8Ec5g5L5oxw