Increase your ingredients by 75%. Easiest way is to multiply all your amounts by 1.75. This would make your yeast amount 3 1/2 tsps, for example.
OOPS. Just found an error in my quick and dirty math. You should multiply by 1 1/3 or 1.33. If you multiply 1 1/2 lbs by 1 1/3 your answer will be 2 lb loaf, for example.
Sorry, I didn’t read my numbers correctly on the first go round.LOL.