This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
You could if you wrote your own custom class loader or, if you set your app to privileged, you could do whatever is is that the manager app does when it restarts an app. It's open source so you can look for yourself.
There is also another option of the <Context .../> element that allow you to make your app reloadable. This will cause the app to be reloaded any time a class file or jar file is uploaded. There is a small performance penalty but it's never been noticable to me.