Hi welcome to
I have gone thru your query  regarding exercise for Wt. loss of umbiblical hernia patient. It is a matter of concern 
If the adult is pregnant, 
overweight and having excess fluid in the abdomen, then 
umbilical hernia occurs. 
The main cause of an umbilical hernia is when fluid, tissue or a part of an organ like the intestine pushes through a damaged part of the abdominal wall.
  Stress aids to the cause of umbilical 
hernias, as stress will intensify 
acid reflux and stomach ailments.
Besides beeing stress free , you  have to increase your immunity by modifying your life style and food habits 
 So, gentle yoga, 
meditation, and different deep breathing exercises along with  intake of balanced diet including  fiber ,minerals ,vitamins in natural forf  permitted fresh  fruit & veges , & antioxidants   are advised to manage stress as well as wellbeing of whole body . 
The obvious solution to consider is to strengthen the affected muscle with simple exercise, repeated often, done regularly at least for 21 days
Though a surgery is recommended by most of the doctors for this disease, there are a lot of natural remedies to get rid of the umbilical hernia.
 which should be tried before you go for  surgery .
I would like to suggest you to Avoid processed foods carbs , sugar , fried ,fast foods , Tea , coffee , alcohol and 
smoking , stress and 
Constipation .
will produce biochemical and metabolic conditions in your body that will decrease your immunity, so avoiding is definitely the first step in the right direction to detoxing the body, boosting immunity .
Take special care to avoid forward bending, hunching, jogging, jerks and things that put outward pressure on your abdominal muscle lining for the next couple of years
It is advised to see your surgeon for further guidance .
Hope this helps solves your query .Take care .All the best .Wish Get well soon .
Don't hesitate to come back in case of any further query .