Good, you're getting it. To give you at least a target with this build(I assume you're, like me, Merchant & Kurokonton too), 1,300+ AP in the chapter 3 and 1,600 AP in the end of chapter 4/encountering scholar Taio are possible numbers to reach with this build.
And no, there's no limit to the AP increase in cycling, by both sources, Hand-seals(Yes, if increases the AP gained too) and Soul Cores.
However, as the friend above said, the first thing you must do in the chapter 3 free-roam is to hunt beasts for Soul Treasures. The calculation of the AP gained by this is:
(Perception x 8 + Survival x 12 + Athletics x 8 + Insight x 8) X Number of months remaining/9.
So, in my runs for example, I have 1 Survival, Perception and 2 Insight. Then I go to the Caravan and use the factotum blessing in Athletics. Cast Western +1 Athletics and Northern +1 Survival. Equip the Weighted clothes and do it in the very first months:
(Perc/1 x 8 + Surv/2 x 12 + Athletics/2 x 8 + Insight/2 x 8) X 12/9 → (8 + 24 + 16 + 16) X 1,333... → 85 + (Weighted Clothes bonuses)
So usually I gain a whole 94 AP from this.
Other builds can gain more since Athletics will be their focuses, but still nearly 100 AP.