They kept backsliding and falling into apostasy. Confession is not enough God will not rescue a people who continue in sin, even when they recognize their sin and confess. Repentance and submission brings deliverance. The people submit to God's judgment and justice. True repentance submits to discipline and correction.
True repentance goes beyond mere confession.
The people repent and reform, doing away with idols. We must return to God when we repent. We must turn from idols, false gods, and the things we trusted in. We cannot repent truly unless we do away with past sins. It brings His forgiveness.