We use to budget 100.00 dollars a day per person...
Now we are more the 125.00 to 150.00 a day per person...
You have 2 teenagers, well simply put... teenagers can eat... alot....
Why you ask... price increase pretty much across the board... that's not just at Disney its everywhere, I'm a local I live in Winter Garden, food cost have gone up everywhere... Adult beverage are not cheap, As well there is always some sort of event going on in Epcot and they have some pretty tasty kiosk offerings...
So for a 21 day trip, I am assuming that you will be leaving the bubble to check-out possibly other parks like Universal or SeaWorld, drive over to the beach, go out shopping.... So when you leave hit up fast food spots McDonald's and let them get the junk food fix... I know that SeaWorld offers an all day dinning pass, it was around 45.00 buck per person, ...not sure if that is available yet, or what restaurants are included... you might want to check it out, if you are going there...
Stock the room with bottled water, soda, juice, gatorade or other sports drinks, you might even want to get you each a water bottle nothing fancy to refill in the parks ice water is free... this will save you alot of money since a bottled water is 4.00 to 5.00 each... Adult beverages for in the room and the cost of pool bar drinks is shocking... We had our grandson, DH got a beer ( 10 to 12 dollars) I got a frozen margarita ( 15 to 20 dollars) , and our grandson got a smoothie ( 12+bucks) so over 40.00 without tip... if you plan pool days them I strongly recommend bring your own adult beverages, you might want to invest in a collapsible cooler, we have one we take everywhere with us, just tuck in the luggage... Stock protein bars, cereal bars, chips, cookies, crackers, cheese sticks, yogurt, a bag of apples or those cutie mandarin oranges. If your kids eat cereal a box of cereal for a nighttime snack is filling, my DD's loved PB&J sandwiches... something else that you might want to consider...
You might want to think about the refillable mugs... not sure if they are available yet ( someone know the answer? ) ... We always have gotten those, morning coffee, refills on soda kids can really go through it...
Are you going to the water parks?... double check what you are allowed to bring into the water parks... We always seem to spend more on food here... lots of treats...