When Your LLM Reaches End-of-Life: A Framework for Confident Model Migration in Production Systems

arXiv cs.AI / 5/1/2026

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Key Points

  • The article proposes a framework for migrating production LLM systems when the deployed model hits end-of-life or must be replaced.
  • Its core method uses a Bayesian statistical approach to calibrate automated evaluation metrics against human judgments, improving confidence in model comparisons even with limited manual evaluations.
  • The framework is demonstrated on a commercial question-answering system handling 5.3M monthly interactions across six global regions, evaluating correctness, refusal behavior, and style adherence.
  • Results show it can identify suitable replacement models while balancing quality assurance with evaluation efficiency.
  • The authors argue the approach is broadly applicable to enterprises operating LLM-based products across many models, regions, and use cases as the ecosystem evolves quickly.

Abstract

We present a framework for migrating production Large Language Model (LLM) based systems when the underlying model reaches end-of-life or requires replacement. The key contribution is a Bayesian statistical approach that calibrates automated evaluation metrics against human judgments, enabling confident model comparison even with limited manual evaluation data. We demonstrate this framework on a commercial question-answering system serving 5.3M monthly interactions across six global regions; evaluating correctness, refusal behavior, and stylistic adherence to successfully identify suitable replacement models. The framework is broadly applicable to any enterprise deploying LLM-based products, providing a principled, reproducible methodology for model migration that balances quality assurance with evaluation efficiency. This is a capability increasingly essential as the LLM ecosystem continues to evolve rapidly and organizations manage portfolios of AI-powered services across multiple models, regions, and use cases.