Code to copy data from sheet1 to sheet2 the first time, and then update after that

Hi
I'm very new to all of this VBA work and am a bit stuck - I have been googling lots of information and this site has provided me with loads of help, but now I need more!

I have a spreadsheet where I wanted to copy 5 columns of data in sheet 1, into 1 column in sheet2. I have managed to do some coding for this (probably a very long winded way around) and the data copies through to sheet2 with no problems. This is the code I've used:

Sub CopyData()
Sheets("WBS - High Level").Range("B4:C20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("E4:F20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("H4:I20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("K4:L20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("N4:O20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("Q4:R20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("T4:U20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
Sheets("WBS - High Level").Range("W4:X20").Copy _
Sheets("WBS - Explanation").Cells(Rows.Count, 1).End(xlUp).offset(1, 0)
Sheets("WBS - Explanation").Select
End Sub

However, if I make changes to sheet1, I can't get the information to update in sheet2 without everything in sheet1 being copied into sheet 2 after the original copy (hope that makes sense!). Can someone help me please!
Thanks

Hi Sean
Thanks for such a quick respons!

The code works, however, it causes me to lose information in rows 1-3 in the WBS - Explanation sheet, which I need to keep. Is there something I can add to only clear rows 4-200 in columns A and B in the WBS - Explanation sheet?

Thanks
Emma

That is just amazing Sean, it works perfectly, thanks so much for your help!!