How to stay in a bots dialog (Bot Framework, C#)

Question

I am currently planing to use dialogs inside my C# bot. I have already designed a complete dialog and implemented it into my current solution but when I test it out, I can only trigger the first part of it.

My bot is configured as following:

protected override async Task OnMessageActivityAsync(ITurnContext<IMessageActivity> turnContext, CancellationToken cancellationToken)
{
    string[] PostCodeDialogStartTrigger = new string[] { "trigger1", "trigger2", "trigger3" };
    if (PostCodeDialogStartTrigger.Contains(turnContext.Activity.Text) /* Maybe || ConversationState != null */)
    {
        await Dialog.RunAsync(turnContext, ConversationState.CreateProperty<DialogState>(nameof(DialogState)), cancellationToken);
    }
    else
    {
        // First, we use the dispatch model to determine which cognitive service (LUIS or QnA) to use.
        var recognizerResult = await BotServices.Dispatch.RecognizeAsync(turnContext, cancellationToken);

        // Top intent tell us which cognitive service to use.
        var topIntent = recognizerResult.GetTopScoringIntent();

        // Next, we call the dispatcher with the top intent.
        await DispatchToTopIntentAsync(turnContext, topIntent.intent, recognizerResult, cancellationToken);
    }
}

I have a set of strings inside PostCodeDialogStartTrigger. I want that the dialog starts when the users message matches one of the triggers. Otherwise my regular process should start, which includes LUIS and the QnA Maker for one-dimensional Conversations. The thing is that i cant stay in the dialog because the next message wouldnt trigger the dialog again, obviously.

Is there a way to check the ConversationState or UserState and if it has progressed, will the dialog continue?