Write the device UUID only when it does not exist

string deviceUUID = "";

using (IsolatedStorageFile appStorage = IsolatedStorageFile.GetUserStoreForApplication())
{
    try
    {
        IsolatedStorageFileStream fileStream = new IsolatedStorageFileStream("DeviceID.txt", FileMode.Open, FileAccess.Read, appStorage);

        using (StreamReader reader = new StreamReader(fileStream))
        {
            deviceUUID = reader.ReadLine();
        }
    }
    catch (Exception /*ex*/)
    {
        deviceUUID = Guid.NewGuid().ToString();
    }

    Debug.WriteLine("Updating IsolatedStorage for APP:DeviceID :: " + deviceUUID);
    IsolatedStorageFileStream file = new IsolatedStorageFileStream("DeviceID.txt", FileMode.Create, FileAccess.Write, appStorage);
    using (StreamWriter writeFile = new StreamWriter(file))
    {
        writeFile.WriteLine(deviceUUID);
        writeFile.Close();
    }

}

catch (Exception /*ex*/)
    {
        deviceUUID = Guid.NewGuid().ToString();

        IsolatedStorageFileStream file = new IsolatedStorageFileStream("DeviceID.txt", FileMode.Create, FileAccess.Write, appStorage);
        using (StreamWriter writeFile = new StreamWriter(file))
        {
            writeFile.WriteLine(deviceUUID);
            writeFile.Close();
        }
    }