The Princess is known to be a majorly popular character at the Reptarland theme park. As explained by Kimi, she regularly makes appearances in the palace at the top of the metal volcano (though this princess is merely animatronic), and she is also an important character in the backstory of Reptar, wherein she sees goodness in the giant lizard's heart whereas everyone else runs away in fear. She then decides to take him in and act as a mother to him. She also appears in the stage performance that retells Reptar's story. Here, she appears on top of a high rock face and begins to sing to the assembled "villagers" that Reptar is not a monster, but more akin to a scared and confused child, and promises to protect him. However, the main antagonist Coco sneaks on stage, snatches the actress playing the princess, and takes her place. She then begins to sing directly to Chuckie, who wants the Princess as his new mother.
You can find Princess gallery here.