Hi, Karla!
Welcome to
planDisney, and thanks for asking us a question. I personally love experiencing the magic of both theme parks in a single day, and I think Park Hopper tickets allow you to make the most of your time!
It is possible for you to upgrade your
theme park ticket to a type of greater value (such as adding the Park Hopper option to a single-park ticket, like you mentioned) by visiting a
Disneyland Resort Main Entrance Ticket Booth in the Esplanade between the two theme parks. If you’ve already used your ticket to make a
theme park reservation, my recommendation is to keep that date and upgrade your ticket upon arrival at the resort, pending availability. That way, you can start your day at the park you originally reserved and then visit the other park after 1:00 p.m. that afternoon with your upgraded ticket as long as capacity allows.
I hope this helps, Karla. Your visit to the Happiest Place on Earth begins soon, and I hope it’s filled with pixie-dusted memories from start to finish!
Wishing you magic,
Courtney