One technique to consider:

If you are adding the columns at the end of your spreadsheet, and they are not included in calculations, try insering a column before the last column. (For example, if you last column is M, add a column BEFORE M). Usually, excel will automatically expand the calculation to include the last column, and it will also apply to new columns. Then, you can copy and paste special the data from that last column into whichever column you want it to be.

Let me know if that works.