Trying to loop a switch with an invalid input (C#)

Anyway I don't know how I'm supposed to go about doing this... in my application I need to have the switch repeat itself if there's an invalid input. All the application does is exit as soon as I enter a different result. Here's my code:

string str = Console.ReadLine(); 
char option = char.Parse(str);
//Need to repeat this switch:
switch (option)
{
    case 'N':
        Console.WriteLine("Creating New App...");
        break;
    case 'L':
        Console.WriteLine("Loading App...");
        break;
    case 'O':
        Console.WriteLine("Loading Options...");
        break;
    case 'Q':
        Console.WriteLine("Exiting Application...");
        System.Environment.Exit(1);
        break;
    default:
        Console.WriteLine("Invalid input.");
        break;
}
Console.ReadLine();


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