Asymptomatic umbilical hernia should be repaired by:

Umbilical hernias are generally asymptomatic protrusions of the abdominal wall. More commonly, the child is asymptomatic and treatment is governed by the size of the defect, the age of the patient, and the concerns of the child and family regarding the cosmetic appearance of the abdomen. When the defect is small and spontaneous closure is likely, most surgeons will delay surgical correction until 4 or 5 years of age. If closure does not occur by this time, it is reasonable to repair the hernia. If a younger child has an extremely large hernia, or if the family or child is bothered by the cosmetic appearance, then repair is indicated. Ref: Schwaz's principle of surgery 9th edition, chapter 39.