A workflow net (WF-net for short) is a Petri net which represents a workflow. There are two important subclasses of WF-nets: extended free choice (EFC for short) and well-structured (WS for short). It is known that most actual workflows can be modeled as EFC WF-nets; and acyclic WS is a subclass of acyclic EFC but has more analysis methods. A sound acyclic EFC WF-net may be transformed to an acyclic WS WF-net without changing the observable behavior of the net. Such a transformation is called refactoring. In this paper, we tackled a problem, named acyclic EFC WF-net refactorizability problem, that decides whether a given sound acyclic EFC WF-net is refactorable to an acyclic WS WF-net. We gave two sufficient conditions on the problem, and constructed refactoring procedures based on the conditions. Furthermore, we applied the procedures to a sample workflow, and confirmed usefulness of the procedures for the enhancement of the readability and the analysis power of acyclic EFC WF-nets.