The “And now” is an textual marker that is used to move the text forward, so there is a logical division in the text. Samuel is moving on to a different point, so there was a logic in the current chapter division. The problem is that the context is temporarily lost. Samuel has been condemning the Nephites, but his message is not simply one of condemnation, but one of repentance. It is still possible to change, and Samuel is making the transition in themes right at this point.
The ending of chapter 14 has the information that man is culpable for his own actions, that he “perisheth unto himself.” (Helaman 14:30). Verse 31 of chapter 14 is the pivot point. Verse 30 has agency condemning man. In verse 31 choice is highlighted again, but in a more hopeful way. After pivoting on the principle of agency from condemnation to hopeful repentance, Samuel now moves to verse 1 of chapter 15 where he explicitly preaches repentance. Chapter 15 flows out of the dynamics set up in the part of the discourse related in chapter 14.