A simple and clean solution would be to put all keys ("ECO", "A", "B1") and their corresponding control names ("lblECO", "lblA", "lblB") in a dictionary and iterate through this for evaluating the individual conditions.
Private mappings As New Dictionary(Of String, String) From
{
{"ECO", "lblEco"},
{"A", "lblA"},
{"B1", "lblB1"}
}
Sub RepComisiones_ItemDataBound()
For Each key As String In mappings.Keys
If valoresRepeter(key).ToString Is "0" Then
DirectCast(e.Item.FindControl(mappings.Item(key)), Label).Text = ""
End If
Next
End Sub