Copy the code below, right-click the sheet tab, select "View Code" and paste the code into the
window that appears.

You can remove or comment out the line

  MsgBox "I just added """ & Target.Value & """ to the list."

if you don't want to be notified when the project list is changed.

You can remove the formula in cell D2 since all it will do in the future is to return the value
entered in C2.

If your named range "projects" is dynamic, then you can remove the lines from On Error Resume Next
to the end.
If it is not dynamic, then those lines will update that named range to include the newest additions.

HTH,
Bernie
MS Excel MVP

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address <> "$C$2" Then Exit Sub
If IsError(Application.Match(Target.Value, Range("A:A"), False)) Then
  Application.EnableEvents = False
  Range("A2").End(xlDown)(2).Value = Target.Value
  MsgBox "I just added """ & Target.Value & """ to the list."
  Application.EnableEvents = True
End If

On Error Resume Next
ActiveWorkbook.Names("projects").Delete
ActiveWorkbook.Names.Add Name:="projects", RefersTo:= _
       "='" & Target.Parent.Name & "'!" & Range("A3", Cells(Rows.Count, 1).End(xlUp)).Address

End Sub