Python Error - RPC Server Unavailable after restarting AUT mid-test

Pretty much as the title says, I have a fairly simple method (all it does is call a method that is part of an item in the program I'm testing and returns that method's result, e.g., "return Aliases.window.panel.item.method(arg)." It works when I start my test run, but I restart the program I'm testing at certain points in the test and after restarting it, the method no longer works, but instead causes this error. Has anybody run into this before? Have a fix or a hint?