Can I start a thread again after it has died?

No, you can't. And the Javadoc for the Thread.start() method tells you that!

From a comment:

Is there anything else I could do to re-start a thread?

You could use ThreadPoolExecutor, which would allow you to pass in tasks and let the service assign a thread to a task. When the task is finished, the thread goes idle until it gets the next task.

So, you don't restart a thread, but you would redo/resume a task.