Howdy, Eliemary! Thanks for stopping by planDisney with your question!
It sounds like you are looking into extending your stay at the Disneyland Resort. With all the fun and magic to be had at the parks, I certainly understand wanting to stay longer! You can upgrade your
one-day Park Hopper ticket to either a two-day Park Hopper ticket or a two-day one-park ticket as long as the ticket you are upgrading to is of equal or greater value than the ticket you currently have. I did a quick check on the Disneyland Resort website and it looks like both of those options should be available based on current pricing.
In order to upgrade your tickets in any way, you must visit a Disneyland Resort ticket booth while your original one-day Park Hopper ticket is still valid. So, if you head straight to the parks with your original ticket, be sure to stop by a ticket booth to upgrade before the parks close that day.
Keep in mind that when you add a day to your ticket, you will need to
make a theme park reservation for that second day either online or on the Disneyland app. It's a good idea to check the
theme park reservation availability calendar to see if there is availability before upgrading your ticket.
I hope this helps! Enjoy your two-day visit to the Happiest Place on Earth!
-Linda