While I was browsing I arrived to a page, a commerical product called: JavaRebel. It offers to reflect development changes without a redeploy or restart. I strongly recommend you to see this demo.
This definetly increases development time but I heard that its not helpful with debugging. If it can be avoided, the product will be more useful.
However this is a commerical product and I hope that there will be such open-source tools, if there are any, please let me know.