update-nic.json

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
      "nicName": {
        "type": "string"
      },
      "SubnetRef": {
          "type": "string"
      },
      "privateIp": {
        "type": "string"
      }
  },
  "variables": {
  },
  "resources": [
    {
      "type": "Microsoft.Network/networkInterfaces",
      "name": "[parameters('nicName')]",
      "apiVersion": "2015-06-15",
      "location": "[resourceGroup().location]",
      "tags": {
        "Role": "Web Server"
      },
      "dependsOn": [
      ],
      "properties": {
        "ipConfigurations": [
          {
            "name": "ipconfig1",
            "properties": {
              "privateIPAllocationMethod": "Static",
              "privateIPAddress": "[parameters('privateIp')]",
              "subnet": {
                "id": "[parameters('SubnetRef')]"
              }
            }
          }
        ]
      }
    }
  ],
  "outputs": {}
}