First, I am really sorry about the impact the incident had on your service. Specifically, for your changing IP, are you currently using the reserved IP feature. You can reserve both your external IP and your internal IP.

External IP: http://msdn.microsoft.com/en-us/library/azure/dn690120.aspx

Internal IP: http://msdn.microsoft.com/en-us/library/azure/dn630228.aspx