Hi Laura! I'm so happy to hear that your family's first Walt Disney World vacation was so magical that you're already planning a second one!
Last year your two-year-old was able to enter the parks without a ticket and could dine free at the buffets, and now that your little one is three, your trip will cost a tad more since you'll have to pay for a child's ticket and meals. While ticket and resort prices tend to increase a bit each year, the cost of your trip shouldn't be drastically more than last year. I suspect the main difference in price is that last year you likely took advantage of a special offer such as a reduced room rate or Free Dining, and those deals haven't been released yet for next fall when you're planning to visit. Keep an eye on the
Special Offers page of the Disney website and on unofficial sites like mousesavers.com and you'll likely see deals for fall Disney vacations posted later this spring. In years past, Disney has offered Free Dining packages and/or discounted resort room rates for fall trips, so there's a good likelihood we'll see similar deals that could save you and other fall travelers quite a bit, and you'll likely be able to take another Disney vacation for an amount closer to what you paid last year.
Other ways to save money on your Disney trip include staying at the reasonably priced Value resorts, bringing breakfast items to eat in your room, taking your own water bottles to the parks instead of buying bottles there, sharing meals at restaurants, buying park tickets from reliable discount ticket brokers (like UndercoverTourist.com) and visiting during non-peak times when the crowds and prices are lower. Where there's a will, there's a way!
Come visit us again at the Moms Panel if you have more questions! We'd love to help!