It just seems like after the Battle of Cannae when the Romans still refused to sue for peace, Hannibal was in a "now what?" mode and was basically reactive to Roman actions. How did he plan to win the war in the subsequent years in Italy?
Hannibal's strategy after Cannae was the same as his strategy before Cannae: disrupt the Roman alliance. Hannibal was at a severe material disadvantage. Bagnall (my source for military commentary on this war) estimates that two years before Hannibal's invasion
the Romans had been able to mobilise 700,000 men, whereas Hannibal's strength after crossing the Alps was only 26,000
(I quote because of this previous discussion with /u/Iguana_on_a_stick regarding these numbers - it seems 700,000 was Rome's capacity, and not the number of men actually put in the field). With such a disadvantage, Hannibal couldn't hope to occupy Italy. Instead he attacked the source of Rome's overwhelming manpower - the alliance system. His thought seems to have been that Rome's allies were allies because Rome dominated them militarily, and if Roman military weakness could be demonstrated, the alliance would crack. The defeats at Trebia, Trasimene, and Cannae demonstrated that weakness, and indeed some of Rome's Greek and Italic allies defected, but not, as far as I know, any Latins. Bagnall suggests that Hannibal stuck to his goal of disrupting the Roman alliance after Cannae in part because of the speed of news: it would take time to see how effective a third defeat would be on Rome's allies.
Meanwhile, he sent his brother Mago to Carthage, where he convinced the Carthaginian senate to open other fronts. They arranged a treaty with Philip V of Macedon to attack Rome's Illyrian province. They also convinced Syracuse, in another Roman province, Sicily, to join the war against Rome. They sent a force of their own to Sardinia, a third province. And of course the Barcids were active against the Scipiones in Spain. They were attempting to prevent Rome from drawing resources from its provinces while Hannibal attempted to prevent Rome from drawing resources from its allies. (NB: anyone who says Hannibal didn't get any help from Carthage is lying or ignorant).
That was the plan. As it turned out, Hannibal wasn't able to crack Rome's alliances enough to hamstring it, and it was able to sustain a war on five fronts, because of that alliance system.
I will hazard a guess: I suspect Hannibal's problem was he didn't understand the nature of Rome's relationship with particularly the Latin allies. I don't think it was one of domination, but more of a partnership. They had rights other Italian allies didn't such as the ability to marry Romans and to become Roman if they moved to Rome, and this allowed a certain participation in Rome's policy-making that wasn't available to others. If you look at the list of defecting allies in the Social War of 90-88 BCE, you see some of the same names, or different names for the same people. Here, this is Livy's list of defectors during Punic 2:
This is Appian's list of defectors during the Social War:
Like in Punic 2, in the Social War the Latins didn't defect.
Preserving even a core alliance, a real alliance and not a military domination, provided Rome with enough resources - barely - to fend off Hannibal in Italy and fight Carthage on four other fronts.