在使用AppServiceConnection时，如果需要重新构建已经运行的应用程序，可以使用以下代码示例：

private async void RebuildAppServiceConnection()
{
    // 关闭旧的AppServiceConnection
    if (appServiceConnection != null)
    {
        appServiceConnection.Dispose();
        appServiceConnection = null;
    }

    // 创建新的AppServiceConnection
    appServiceConnection = new AppServiceConnection();

    // 设置AppServiceConnection的PackageFamilyName和AppServiceName
    appServiceConnection.PackageFamilyName = "PackageFamilyName";
    appServiceConnection.AppServiceName = "AppServiceName";

    // 打开AppServiceConnection
    AppServiceConnectionStatus status = await appServiceConnection.OpenAsync();

    if (status == AppServiceConnectionStatus.Success)
    {
        // AppServiceConnection已经重新构建成功
    }
    else
    {
        // AppServiceConnection重新构建失败
    }
}

在代码示例中，首先关闭旧的AppServiceConnection，然后创建一个新的AppServiceConnection，并设置PackageFamilyName和AppServiceName。最后，调用OpenAsync方法打开新的AppServiceConnection。如果OpenAsync方法返回的AppServiceConnectionStatus为Success，则表示AppServiceConnection已经重新构建成功；否则表示重新构建失败。