Overlay text of labels

In this example the text of the labels are re-drawn and overlay each other when pressing the button. Is there a possibility to clear the layout mGridLayout before calling Initialize()? Or is the only solution to save the labels globally and simply set the text instead of creating them each time?

Code:

MyDialog::MyDialog(QWidget *parent, Qt::WFlags flags)
	: QDialog(parent, flags)
{
	// test input
	mTermName.append("term 1");
	mTermName.append("term 2");
	mValues.append(1.23);
	mValues.append(3.4322);
 
	QGridLayout *mMainLayout = new QGridLayout(this);
	mGridLayout = new QGridLayout;
	Initialize(); // initializes mGridLayout with its content
	mMainLayout->addLayout(mGridLayout, 0, 0);
 
	QPushButton *btn = new QPushButton("press me");
	Q_ASSERT(connect(btn, SIGNAL(clicked()), this, SLOT(slotPressed())));
	mMainLayout->addWidget(btn, 1, 0);
 
	setLayout(mMainLayout);
}
 
 
void MyDialog::slotPressed()
{
	mValues[0] = 2.5;
	Initialize();
}
 
void MyDialog::Initialize()
{
	int nbrTerms = 2;
	int row = 1;
	for(int i=0; i<nbrTerms; i++)
	{
		QString termName = QString("%1").arg(mTermName[i]);
		double termValue = mValues[i];
 
		QLabel *nameLabel = new QLabel(termName);
		QString parameterValueText = QString("%1").arg( termValue, 1, 'f', 3 );
 
		QLabel *termValueLabel = new QLabel(parameterValueText);
		mGridLayout->addWidget(nameLabel,	 row, 1);
		mGridLayout->addWidget(termValueLabel,row, 2);
		row++;
	}
}