How to Force New Google Spreadsheets to refresh and recalculate?

What worked for me is inserting a column before the first column and deleting it immediately. Basically, do a change that will affect all the cells in the worksheet that will trigger recalculation.

File -> Spreadsheet Settings -> (Tab) Calculation -> Recalculation (3 Options)

• On change
• On change and every minute
• On change and every hour
  This affects how often NOW, TODAY, RAND, and RANDBETWEEN are updated.

but.. .. it updates only if the functions' arguments (their ranges, cells) are affected by that.
  

from my example
I use google spreadsheet to find out the age of a person. I have his birth date in the format (dd.mm.yyyy) -> it's the used format here in Switzerland.

=ARRAYFORMULA(IF(ISTEXT(K4:K), IF(TODAY() - DATE(YEAR(TODAY()), MONTH(REGEXREPLACE(K4:K, "[.]", "/")), DAY(REGEXREPLACE(K4:K, "[.]", "/"))) > 0, YEAR(TODAY()) - YEAR(REGEXREPLACE(K4:K, "[.]", "/")) + 1, YEAR(TODAY()) - YEAR(REGEXREPLACE(K4:K, "[.]", "/"))), IF(LEN(K4:K) > 0, IF(TODAY() - DATE(YEAR(TODAY()), MONTH(K4:K), DAY(K4:K)) > 0, YEAR(TODAY()) - YEAR(K4:K) + 1, YEAR(TODAY()) - YEAR(K4:K)), "")))

I'm using TODAY() and I did the recalculation settings described above. -> but no automatically refresh. :-(
It updates only if I change some value inside the ranges where the function is looking for.

So I wrote a Google Script (Tools -> Script Editor..) for that purpose.

function onOpen() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheetMaster = ss.getSheetByName("Master"); 
  var sortRange = sheetMaster.getRange(firstRow, firstColumn, lastRow, lastColumn);  

  sortRange.getCell(1, 2).setValue(sortRange.getCell(1, 2).getValue());
}

You need to set numbers for firstRow, firstColumn, lastRow, lastColumn

The Script gets active when the spreadsheets open, writes the content of one cell into the same cell again. That's enough to trigger the TODAY() function.

Look for more information on that link from Edward Moffett: Force google sheet formula to recalculate.