Hi Casey!
Welcome to the Disney Parks Moms Panel. It's never too early to plan for your next trip and purchasing your tickets as early as you can is always a great idea!
When you purchase tickets to Disneyland Resort, there will be an associated
validity date with your ticket. As long as your
tickets are still within the validity window, you would not be required to pay the difference in any price increase. The exception to this rule would be if you purchased a Single Day Ticket and you purchase for a Value day and later would like to visit on a Regular or Peak day, then you would need to pay for the difference in price and it would be the price associated on whichever day you upgrade. While validity dates are subject to change for future ticket purchases, currently if you purchase a Single Day Ticket they are valid through December 30, 2020. If you purchase a Multi-Day ticket, they are valid for use through January 12, 2021 or 13 days after their first use, whichever comes first.
I hope this helps in planning your upcoming visit to
The Happiest Place on Earth! Please come back and let us know if we can help in any other way.
-Lindsey