Sprinkle salt and pepper over chicken and place chicken in slow cooker. Add bay leaf and lemon juice. Cover. Cook on low for 6-8 hours, or on high for 3-5 hours. Remove chicken from bones. Reserve liquid, skimming fat if desired.
Cook 1/2 cup liquid, celery and onions in microwave on high for 2 minutes. Add frozen vegetables and microwave until cooked through. Return all ingredients to slow cooker and cook on high for 30 minutes.