Thank you, Angela. That was the fix. Essentially, what you need to do is to set a field value BEFORE you submit the form. So, I have a StoredProcedure that gets a guid from SQL Server when the page loads. Then, I have a validation function that fires when the user clicks submit. Inside that validation function, I simply set the Print_TicketID = the guid value and submit the form. When the form comes back around, (after workflow), it now has that guid in the query string of the url. The first thing I do in the form (In the lookup complete function) is check for a value in that field. If there is one, I open up a hidden IFRAME and point it at the ticket url, handing it the guid. When the IFrame is ready it calls back to the main form that it's ready to be printed, so then I get the contents of the IFrame and print it. This sounds really complex but it's not that bad. I'm including the code here for anyone who wants it.

$(document).ready(function () {

  $('.Submit').click(function (e) { validateForm(e); });
  $('#q0').append("<div class='hidden' id='print_output'></div>");

  var eventMethod = window.addEventListener ? "addEventListener" : "attachEvent";
  var printEvent = window[eventMethod];
  var messageEvent = eventMethod === "attachEvent" ? "onmessage" : "message";
  printEvent(messageEvent, function (e) {

    if (e.data === "printme" || e.message === "printme") {
      $("#myiframe").get(0).contentWindow.print();
      $('.print-ticket-id input').val(null);
    }
  });

  $(document).on('lookupcomplete', function (e) {
    //Field152 is the Print_TicketID field
	if (e.triggerId == 'Field152') { 
      if ($('#Field152').val()) {
        if ($('#Field152').val() != null) {
          print_receipt();
        }
      }
    }
  });
});

function print_receipt() {

  var domain = document.location.hostname;
  var receipt_url_root = "http://" + domain + "/Forms/";
  var receipt_url = "";

  if ($('.print-ticket-type-id input').val() == 1) {
    receipt_url = receipt_url_root + "PinGageReceipt?guid=" + $('.print-ticket-id input').val();
  }
  if ($('.print-ticket-type-id input').val() == 2) {
    receipt_url = receipt_url_root + "ThreadReceipt?guid=" + $('.print-ticket-id input').val();
  }

  if (should_print_receipt == true) {
    if (receipt_url != "") {
      loadiFrame(receipt_url);
      should_print_receipt == false;
      $('.print-ticket-id input').val(null).change();
    }
  }
}

function validateForm(e) {

  if (!$('.print-ticket-id input').val()) {
    //'.guid input' is the NEW guid that SQL server gave us when the form loaded
    //so that when we submit the form, our new guid will already be in there.
    $('.print-ticket-id input').val($('.guid input').val());
  }
  
  //do other stuff
  
 }
 
//THIS code is from the ticket. It calls back to the parent when it is ready.
$(document).ready(function() {
  $(document).on("onloadlookupfinished", function() {
    parent.postMessage("printme", "*");
  });
});