You do have one bit of publicity gold -- the large organisation who followed one of them. You need to keep them interested, so at least keep that account active. Maybe get him to tweet something interesting at the organisation (can't remember which character it was, but one of them was a fan of LFC). Maybe get the guys to follow some real-life people too, especially ones mentioned in the story.
Sure, the accounts won't really work unless you get published, but it won't need much time to keep them active. I'd say pick a time in the story when the two characters are busily engaged with each other, and throw a few tweets between them for this time -- a bit of football, a bit of innuendo. Also, maybe, make a couple of fake fans' accounts and tweet the lads.