I wouldn't recommend it. Cooked salmon is best when eaten right away. Reheating salmon burgers often overcooks them and makes them tough and rubbery. Luckily, salmon is one of the fastest cooking proteins and can be ready in less than 20 minutes. If you're looking for ways to prep ahead when hosting, you can make the slaw dressing and marinate the salmon ahead of time. Then, bake the salmon and add the dressing to the cabbage just before serving.