You can refreeze it several times. Bring it to a boil each time before using it or refreezing it.
The yellow rice mix has seasonings in it that include flavoring in place of the stock so you wouldn't notice a great difference.
Save the stock for soup, stew or rice dishes from scratch.
Next time you make stock, freeze it in portion sized containers. One or two cups for recipes, ice cube trays for sauces, quart sized Ziplocks for soups and stews.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan