1) Download the most current JRE (Which at the time of this blog post was Java SE 7u21)
http://www.oracle.com/technetwork/java/javase/downloads/index.html
2) Install it to an easy to remember folder, such as C:\jre\
3) Stop the Tomcat Railo service ( while it is not busy )
4) Rename Railo's JDK folder: railo/jdk --> railo/jdk_old ( In my case, C:\railo\jdk )
5) Make a new railo/jdk folder
5) Copy the contents of C:\jre from step 2 into the railo/jdk folder
6) Restart Tomcat Railo & Test your world. You can display the jre version in coldfusion via:
<cfoutput>#CreateObject("java", "java.lang.System").getProperty("java.version")#</cfoutput>
7) Recycle railo/jdk_old
https://github.com/getrailo/railo/wiki/Installation%3AInstallerDocumentation%3AMSUpgradingJRE