Depending on the cause, various solutions can be offered. The uvula can be enlarged due to general dehydration. The arid air, as well as normal breathing over night, can dry the uvula mucosa. Drinking enough water can help a lot.
An allergic reaction can cause the uvula to enlarge. Allergic tests should be done to determine the exact allergen and to avoid it.
Sometimes even inflammation due to an infection can cause swelling of the uvula. It is usually accompanied with inflammation and swelling of the throat mucosa, also. Antibiotics are the adequate remedy in that case.