All certifications - Emergency First Aid with CPR B, Standard First Aid with CPR C, Bronze Medallion, Bronze Cross, and National Lifeguard are valid for 2 years. You will not have to take another course next year.
After two years, you will have to take a re-cert course, which is typically 4-5 hours per certification. You will have to re-cert your first aid and the highest lifeguard certification only. (Eg. either Bronze Cross, or National Lifeguard - not both).