3 options i can see
Option 1
Contact a strap maker (this will most deffinatly be the most expencive option i would have though)
Option 2
Have a look on american forums, no doubt someone over there has made a hello kitty strap before
Option 3
Make your own, find some material, cut it to the size you want/ need it and then try and duplicate your existing strap. Then what you want to do is double strap your gogs, im sure you dont need explaining what this is? but if so then feel free to ask. By using a double strap you are using the underlaying strap as the bit that actualy secures it to your head and then material can just be pulled snug and will cover the existing strap
Note - i have no idea how this will look, just an idea, ive double strapped when ive used retro JT straps which are mega expencive but thats just to stop stretching
