Refresh a Combobox in C++?

I have a function that detects camera ports in 3D slicer, however it seems to only run once. When I unplug/plug in a camera, the number of ports should update in a combobox (designed in Qt), but nothing changes.

The function I'm using detects when the camera port is clicked:

void qSlicerTrackingModuleWidget::onCameraPortClicked(){
  Q_D(qSlicerTrackingModuleWidget);

  // Clear current entries
  d->CameraPortComboBox->clear();

  int n = 0;

  // Loop over camera ports until last one is found. Add all available ports to combo box and exit.
  while(1){ 
    cv::VideoCapture cap = cv::VideoCapture(n);


    if(!cap.isOpened()){ 
      return;
    }
    QString portNum = QString::fromStdString(std::to_string(n++));
    d->CameraPortComboBox->addItem(portNum);
    qSlicerCoreApplication::processEvents();
  }
}

The setup function runs last and assigns the GUI to the actual function.

connect( d->CameraPortComboBox,   SIGNAL(clicked()),  this, SLOT(onCameraPortClicked()));

I need it to refresh and try to detect the cameras every time the combobox is clicked on, but because of the interface setup I am not sure if it is possible. I don't think constantly refreshing the program is a good option, so I'm out of ideas. Is there any way to do this?