Vedavati refuses to curse Ravana as it would exhaust her tapasya, but pledges to return in another age and be the cause of his destruction.
In some versions of the Ramayana, Vedavati is reborn as Maya Sita, who takes Sita's place and is abducted by Ravana and suffers his captivity, while the real Sita hides in the fire.
The Rishi Agastya tells Rama that Vedavati was reborn as SWAHA, Agni's Wife and became the cause of Ravana's destruction at his hands.
Excerpt from Skanda Purana regarding this rebirth-
"In treta yuga, when I had incarnated as Ram, Ravan had deceitfully abducted my consort Sita. But fortunately she was not Sita butAgni's consort Swaha. Before this incident could occur,Agni had already taken Sita to Patalloka and kept his own wife 'Swaha' in her place. Indra's act had special purpose behind it--to avenge Swaha's death,who was Vedavati in her previous birth and who had committed suicide after being touched by the same demon.Actually, Agni's consort 'Swaha' was 'Vedavati' in her previous birth. So, in reality Ravan had abducted Vedavati instead of Sita. Later on, I thanked Agni and promised him that I would make Vedavati my consort in Kaliyuga. The same vedavati has taken birth as Padmavati. You must go and convince Padmavati to become my consort.Vakulmalika went to Narayanpur and informed the king about Sri Hari's desire. Emperor Akash was extremely delighted at the prospect of having Sri Hari as his son-in-law. An auspicious day was chosen for the marriage and thus, Lord Sri Hari got Padmavati as his consort."