As mentioned in the comment, you could use the ItemDataBound event for this.
This example is in VB - been a while since I wrote C#, though will give you an idea. I haven't checked it for syntax either, it's more an example to get you up and running.
In your <ItemTemplate>
add yourself, say, a ASP:Label
. In this case, it's called myLabel
So in your code behind, create a private method that will handle the ItemDataBound
event.
Protected Sub myRepeater_ItemDataBound(sender As Object, e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles myRepeater.ItemDataBound
If (e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem) Then
Dim uG As URLGroup = CType(e.Item.DataItem, URLGroup)
'' you now have the group for that one item
'' you should now be able to get additional information needed.
'' you can also get the myLabel from this item
dim lbl as Label = CType(e.Item.FindControl("myLabel", Label)
'' and set its text to whatever you need
lbl.Text = MyCounter
End If
End Sub
Hopefully this will get you on your way.
Here is a link to the MSDN documentation for it too.