Re-deploy spring boot service without restart?

What about JRebel plugin. It worked perfectly for me, but, unfortunately, it's not a free app. Like alternative, (i used this approach with Spring MVC, with Spring Boot it could be otherwise), I set up a soft link in work directory on a compiled path in JBoss (in my case it was dir with name target and *.class and *.jar files). As for me, the first solution with JRebel is the most appropriate for you.