The Little Mermaid 2: Return to the Sea was released in 2000 and follows on from the events of the first film. Ariel and Eric are happily married and now have a daughter named Melody. When it's time for her to meet the mer-people, Morgana, Ursula's sister, vows revenge for her sister's death and therefore Ariel forbids any contact with the ocean. But, as Melody grows older her curiosity leads her to the ocean again to discover her roots and stop Morgana from executing her evil plan.
The Little Mermaid: Ariel's Beginning was released in 2008 and is a prequel to the first film. After her wife's death, King Triton forbids music in all the realm. But when Ariel discovers it, she will do anything to bring it back to her father and all the kingdom.
In the meantime check out the new trailer announcing this release:
Meanwhile, the original 1989 classic will be released as a 'Diamond Edition' on 2nd September in the UK and 1st October in the US.