Replace when the business model, operating needs or technology constraints have moved far enough that the current ERP blocks necessary change. Modernise when the core system still fits but pain comes from process design, integrations, reporting, data or poor use of existing capability. Diagnose the source of the problem before comparing products.
Separate symptoms from causes
Slow reporting or duplicate entry may come from integrations and ownership rather than the ERP core.
Model the transition
Replacement creates migration, integration, process, training and operating-model work that is often larger than the licence decision.
Use idealized design carefully
Ask what the business would want the future operating model to look like if the current ERP were not dictating the answer, then work back to a feasible transition.
How soapplied approaches the question
I would not start by assuming the stated problem is the whole problem. The first step is to understand the people, purpose, constraints and interactions around it, then test what intervention would improve the system rather than merely optimise one component.