Reduced participation may depend on schedules, distance, or difficulty in understanding topics. Interpreting it immediately as disinterest risks hiding modifiable obstacles. Before changing the format of meetings you need to know the conditions that make it difficult to be there.
I propose to collect brief feedback from those who participate little, keeping the response voluntary. The question should be about concrete obstacles and how to use them. The forms of participation and the deliberative procedures remain those applicable to the cooperative; the reconnaissance serves the organizational design.
In a hypothetical example, some members may be absent because the meetings coincide with the most intense moment in the store. Others may not recognize a link between the agenda and business problems. The two situations require different interventions.
The next verification looks at whether the change reaches previously little-present people. The sheer growth in the number of participants does not prove a better discussion. The aim is to create understandable conditions to contribute, keeping attention to the quality of the information and the continuity of the relationship with the members.