What kind of discharge she is having from umbilicus?
Is it smelling like stool or just sticky?
Discharge can happen due to umbilical granuloma ( remains after cord falls off) or can be if there is any connecting tract till intestine.
Antibiotics wont help.. ..
Salt can tried locally , if doesnt resolve in 2 weeks, then go ahead with surgery.
Next Steps
consult pediatric surgeon and get operated if they suggest.