Is there a way to regenerate attraction?

Have they asked each other about attraction since you changed the TOTOs? That should have them review their opinion on a sim based on their TOTOs and everything they know about the other sim. 

It's an interaction under the new social category.

Is the romance bar red? Do they have negative sentiments towards each other? If that's the case, then nothing but time and treating each other better in game will fix it. If one has a major negative sentiment it either has to decay over time or be replaced with another equally powerful positive sentiment.

If you still want them to be soulmates, you may need to play out an enemies to lovers story with them.

If that's not it, then I don't know what's wrong. It may be a bug in game.

There is no physical attraction in game, just compatibility based on likes, dislikes, turn ons and turn offs and traits. You can edit likes and dislikes, turn ons and turn offs, but there is nothing you can do about how the traits interact with each other to create compatibility between the sims. Maybe you could change traits or go to counselling classes and work on the relationship, but my understanding is that as long as the romance bar is full they are a solid couple. 

Hmm... I tried my best to understand it...

Have you tried setting them in CAS? It's simple: just open the Simology panel (the place where the traits and aging bar are), scroll down until you reach likes and dislikes section, and in there there's a button to edit them in CAS. Turn-ons and turn-offs can be changed there.

Or did the other teens not in the rotation generate these? In this case, go to Manage Worlds, open Manage Households panel (top right button), and find those teens. Once you found the household they're in, click on them, then you can edit them in CAS.