Can I create a self updating module in excel?

Question

So I have a column with data that need to be simplified.

ColumnA      ColumnB  

Cyan          Blue  
Navy          Blue  
Forest        Green  

I want to write a module that would ask me what to do about cyan when it first encounters it and I have to input blue. But for all the instances that cyan is encountered after this, the corresponding column B needs to be blue.

Answer 1

Sub SIMPLIFY()
    RECORD_COUNT = Range("A" & Rows.Count).End(xlUp).Row
    For i = 1 To RECORD_COUNT
        If WorksheetFunction.CountIf(Columns("A"), Range("A" & i)) > 0 Then
            RECORD_ROW = WorksheetFunction.Match(Range("A" & i), Columns("A"), 0)
            If Cells(RECORD_ROW, 2) <> Empty Then
                Cells(i, 2) = Cells(RECORD_ROW, 2)
            Else
                Cells(i, 2) = InputBox("Input Color for " & Cells(i, 1))
            End If
        End If
    Next i
End Sub

Copy above code to worksheet VBA. The code waits for any changes in column "A" and checks for previous data. It inputs color automatically if it exists, or it asks for color when it's new.