Other than recognizing the value of his generals as more than just a pawn to be used, Hannibal is pretty much all out of option.
Most of his major achievements rely heavily on the Numidian cavs, which is something he doesn't have anymore.
Giving more detail to the strategy around this might give a bit more nuance (at the risk of making a useless heavy exposition that's just a bore to read), but Carthage is basically fucked ever since they loss the Iberian peninsula. If the start of the manga is Rome's losing streak, then the ending is Carthage's.