Automatic configure wordpress IP on EC2

I have installed a LAMP server on an EC2 instance. Then I created an AMI so that I can easily spin up instances in the future.

Today I went back to spin up one such instance, and to my surprise the IP in the configuration is wrong. Basically when I first installed the LAMP server, Wordpress detected the IP and configured accordingly. Now on the instance that I launched today the IP is different, but the configuration for the previous IP is still there.

Now, I know how to change Wordpress IP. My question is: How can I make this step automatic when I launch an EC2 instance from an AMI?

Thanks