Some States require you to add a language for some years.
Some CORE Programs and Just Good Books include some language references and lessons:
If you require something more structured, especially for high school, we suggest:
DUOLINGO - A Free App
Rosetta Stone - our favourite comprehensive language learning program
There are group discounts for Rosetta Stone available through some homeschooling groups and various other online outlets. We are currently enquiring about discounts that may be offered through Simply Homeschool.
Another option is to purchase Rosetta Stone Homeschool Version as a box kit with multiple licences to share with other families near you.