Remove skin and chicken meat from the rotisserie chicken. Reserve meat for later.
Place chicken ccarcass; skin and bones in a large stockpot. Add the chopped onion, celery leaves, carrot peels, parsnip peels, and garlic cloves to the stockpot. Add enough water to cover all the ingredients.
Bring to a boil and simmer on low, covered for 90 minutes.
Strain off broth; removing chicken bones, skin, and all the vegetable peels from the broth and discard them. Use a spoon to skim off any excess fat from the broth. Return broth to the stock pot.
Add bay leaves, sliced celery, carrots and parsnips to the strained chicken stock. Bring to a boil over high heat. Reduce heat and simmer until carrots and parsnips are tender, about 15-20 minutes.
Add the reserved shredded rotisserie chicken and chicken bouillon to the pot and stir to combine. Cover and simmer on low until chicken is heated through.
Fish out bay leaves and discard. Season with salt and pepper to taste.
Add vermicelli to the pot and simmer until noodles are soft, about 4-5 minutes.
Remove from heat and add a squeeze of fresh lemon juice.
Serve soup hot.