Yes, everyone above is correct.
If you booked a PACKAGE and were quoted an exact price, Disney will not change that price. The ONLY way you would have to involuntarily pay more for a booked, price-quoted package is if the state or county sales tax increases. This happened to me for my 2006 trip. Disney contacted us and explained the reason for the price increase. They can't insulate us from government taxation.
Now, let's say you booked a room-only reservation. Most people don't know this, but you can add tickets to a room-only reservation without automatically making it a package. Doing so saves you a few minutes at check-in if you were otherwise going to purchase your park tickets at the resort, anyway. But in booking it this way, you are merely "reserving" the tickets or letting Disney know of your intent to buy them. If Disney increases their ticket prices between the time you booked the room-only reservation and the time of check-in, then in that case you'd have to pay the "new" ticket price, since you didn't actually book the ticket, you just let them know your intention to buy it.
Details, details .... :brick: