  Like software, requirements evolve and change frequently during the
development process. Refactoring is the process of reorganising software
without changing its behaviour, to make it easier to understand and modify. We
propose refactoring for formalised requirements to reduce repetition in the
requirement set so that they are easier to maintain as the system and
requirements evolve. This work-in-progress paper describes our motivation for
and initial approach to refactoring requirements in NASA's Formal Requirements
Elicitation Tool (FRET). This work was directly triggered by our experience
with an industrial aircraft engine software controller use case. In this paper,
we reflect on the requirements that were obtained and, with a view to their
maintainability, propose and outline functionality for refactoring FRETISH
requirements.
