The behavior that you are observing is due to the fact that you are adding the new value to the Cell.Text property, which will lead to the removal of all controls in the Cell.Controls collection.
For achieving the desired result you could traverse through the Controls collection of the Cell and change the Label control text instead. Bellow is an example of that approach:
Literal).Text = (e.Cell.DataItem).ToString().Remove(0, 2);
Please give this a try and see if the result meets your requirements.
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