Add new FileServer locations after startup (edit middleware after startup)

My web application needs to let an admin user add and remove served folders from a .net core 2 app. I have found a way to provide a list of served folders, but I can't find a way to dynamically add or remove them once the app has been configured.

How do I re-run the configure function from within the application? Alternatively, how do I add or remove UseFileServer() configurations within an already-running service?

public class Startup
{
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseDeveloperExceptionPage();
        app.UseMvc();

        //get these dynamically from the database
        var locations = new Dictionary<string, string>{
            {@"C:\folder1", "/folder1"},
            {@"D:\folder2", "/folder2"}
        };
        foreach (var kvp in locations)
        {
            app.UseFileServer(new FileServerOptions()
            {
                FileProvider = new PhysicalFileProvider(
                    kvp.Key
                ),
                RequestPath = new PathString(kvp.Value),
                EnableDirectoryBrowsing = true
            });
        }
    }
}

I'm using .net core 2.0.0-preview2-final.