When a roadmap keeps slipping, the instinct is often to blame the architecture. In our experience, it's just as often a capacity problem wearing an architecture costume.
If your team can clearly describe what needs to be built but doesn't have the hours to build it, augmentation gets you back on schedule in weeks. A rewrite, on the other hand, is the right call only when the team can't confidently describe how the current system behaves.
Knowing which situation you're in before committing budget is the difference between a two-month fix and a year-long detour.