It all comes out in the wash.
Your refund or the amount you owe is the difference between your income tax liability, (i.e., tax calculated on your taxable income), and the amount you've had withheld. You got a slightly higher paycheck because less tax was withheld so you'll have a slightly lower refund. It's simple math.
Changing LAST YEAR's W-4 can't change anything because that year is over and done with. Changing THIS YEAR's W-4 is all you can do.
