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.
The lack of a response might indicate that there's no such option. Just kicking the can myself, I can't think of one that would tell WebSphere Application Servers to remove a running Java class file from memory, and replace it with a new one, without bouncing the application itself first.
In IRAD7.x, we just republish, but that usually causes the WebSphere test server environment to stop and start.
I'm happy to be proven wrong on this point though.