This question really boils down to logistical planning and corrective actions. There is more than one way to try to fix this situation. IF a case can be made for showing that the plan is now back on track, THEN one can attempt to show USCIS that job creation is right around the corner. In other words, show that the plan is "on the cusp of achieving the goals".
As an alternative, the earlier I-526 approved investors could re-file new I-526 petitions and file for adjustment (or re-adjustment) in order to trigger a new conditional period. It is a fact-specific situation. The worst danger of starting over is if one has children who have "aged-out" of eligibility for derivative visas.