The antonym for "slipped back" would be "moved forward." Moving forward means making progress or advancing in a positive direction, while slipping back means regressing or undoing progress. Moving forward may involve taking steps to achieve a goal, pushing oneself out of one's comfort zone, or simply making positive changes in one's life. On the other hand, slipping back may involve giving up, succumbing to fear or doubt, or faltering in one's commitments. By moving forward, one can achieve success, happiness, and fulfillment, while slipping back can lead to frustration, disappointment, and regret.