There are a number of wonderful resources to help you maintain and improve your home language skills. Many communities have Saturday schools or similar weekend/evening programs to help students of all ages practice home language. UW and community colleges also offer a wide range of language classes (you may even be able to earn credit for these!) There are also local meetups of individuals who want to practice a language together; they may meet at a coffee shop or community center to work on their language skills in a  conversational setting.
If you are comfortable doing so, start at home! Ask your family members to speak your home language with you. While doing simple chores around the house or eating a shared meal, you will have countless opportunities to practice and develop your home language. Attend community events, speak with your elders, listen to music, watch movies in your home language with your family, and find other ways to do day-to-day activities in your home language. Before you know it, you will feel your language skills getting stronger!