The 21-year-old has been in hospital since Saturday when husband Nick Gordon found her unresponsive in the bathroom of their Georgia home.
Her family issued a new statement overnight, saying: "Bobbi Kristina is fighting for her life and is surrounded by immediate family. As her father already stated, we are asking you to honour our request for privacy during this difficult time."
Bobbi's father is singer Bobby Brown.
A previous statement issued by him said: "Please allow for my family to deal with this matter and give my daughter the love and support she needs at this time."
Representatives from the Georgia hospital treating Bobbi will not comment on her condition, citing medical privacy laws, and the Roswell Police Department have said no further information will be given at this time.
Bobbi was discovered unresponsive at her home on Saturday, 31 January. Many have pointed out the similarity to the death of her late mother Whitney in 2012.
Legendary singer Whitney was discovered dead in a bathtub at a Los Angeles hotel just hours before the Grammy Awards.
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