The thing is that now that African Arabo-Muslims took and held Sicily, the situation is no longer the same than during its conquest. Byzantine had the advantage of terrain, of adaption.
I mean, Maniakes managed to get the eastern coast for a short time, and it was already costing in men and effort.
Now, they lost it, and if they could to well, a complete reconquest of Sicily is unlikely.
Pantellaria was took since the VIII, and during two centuries the island knew continual raids without any real sucess to counter theses. The sea was already in great part Islamic and the resistance of Byzantines terrerstrial.
Furthermore, the Muslims did well in Sicily, with the western half of the island quickly islamized.
Finally, as Sicily was on the Fatimid sphere of influence, the Byzantines could hesitate to have a potential ally frowning upon such a tentative of reconquest.