If you decide to change (higher or lower) Windows Azure Application instance count, you can do it directly from Windows Azure Portal. The instruction are as below:

Please login to Windows Azure Management Portal. Now select your service which instance count you would want to change and use "Configure" option from the top ribbon as below:

Above action will open a dialog in which you can edit the Service Configuration to edit instance count as below:

Finally once you finish above step you will see the instance count increases as below: