Is it necessary to file a lawsuit to prove the daughter's lineage after the mother was accused of her not being my daughter?

The child belongs to the [owner of the] bed, and if paternity is established, it cannot be denied except through li'an (mutual imprecation). The default is that the daughter is attributed to you, and you do not have the right to deny her paternity from you. However, if you are strongly convinced that your wife is truthful in denying the daughter's paternity from you, then you must deny her paternity through li'an.