Hopefully it was the rap song and/or Scuttle's song.I guess the fifth song they wrote got cut
As for the reprises, they're probably repeating what happened with Aladdin, where there was a "One Jump Ahead (Reprise 1)" and "One Jump Ahead (Reprise 2)." I loved that addition, so I'm hoping they might do the same here, perhaps have Ariel sing sadly on the rock before Triton decides to make her human. I didn't open the link you posted Sotiris, but the sad reprise I've described here before (the one where she says, "I'd give my life, I'd sell my soul, because I can feel I'll never be whole") was supposed to be where POYW (reprise) was in the original film, only they rightly decided to have something more daring and triumphant instead. They could definitely use pieces of that one if they have her sing on the rock ("But I can see...I'll never be poyw"), only for Triton to rise at a distance, hearing what she's saying and taking pity on her.