Hi Matthew, welcome to planDisney!
I have GOOD NEWS! You can certainly upgrade your one park per day ticket to a park hopper ticket! I have found that the easiest way to do this is by visiting the
Disneyland Resort Main Entrance Ticket Booths. If that's difficult for you, I suggest calling the
Disneyland Resort Ticket Line at 714-781-4636 and inquiring with the amazing Cast Members to help upgrade your ticket.
OH! And one more thing, if you have not added the new
Disney Genie+ service to your ticket yet, I highly recommend you consider it! Genie+ allows you to access the
Lightning Lane entrances for certain attractions and skip the standby lines. My family and I always purchase Genie+ during our visits. The amount of time we save by skipping the standby lines is huge! AND, another great perk, you also get unlimited
Disney PhotoPass Digital Downloads with your purchase of Genie+!
I'm excited about your upcoming trip! In the meantime, if you have any more questions, please visit us again!
See ya real soon!
Jin