What are best practices and/or tools for updating AMIs on a regular basis?
We are planning to automate this process for our Jenkins EC2 slaves.

Currently we have to manually update the AMI ID every time we build a new AMI, but by taking advantage of the config.xml file where Jenkins store all its configuration, we should be able to automatically update the AMI value in this file and then restart Jenkins to take those changes into effect.

EDIT: see comments below for a better way to make those changes rather the config.xml file