Yesterday, I wrote how to Update your Azure CLI with Choco. Today, I needed to renew an existing Service Principal Name in an AAD. A SPN stands for Service Principal Name which is used for automation authentication. The PowerShell az module got some updates (v1.0.0). So, here´s the full step-by-step instruction for renewing a SPN with az ad sp credential.
This updates the steps described at How to create or renew Service Principal Names in Azure Active Directory… 
az login
rem As a quick reminder, if you have multiple Azure subscriptions, get them and then select one…
az account list --all --out jsonc > C:\temp\mysubscriptions.txt
az account set --subscription "[subscriptionname]"
rem Get a list of all SPNs and write it to a file for easy handling...
az ad sp list > c:\temp\myspns.txt
rem Search for your desired [SPN-ID]...
az ad sp show --id "[SPN-ID]"
az ad sp credential list --id "[SPN-ID]"
az ad sp credential reset --name "[SPN-ID]" --years 2
You get a result like this:
{
"appId": "[SPN-ID]",
"name": "[SPN-ID]",
"password": "[Some-new-password]",
"tenant": "[Tenant-ID]"
}
Renew the new password in your existing or new apps.
Hope these quick steps help!