Good PR in the run-up is important to make the project known. But also during the participation it can be useful to take measures to advertise the project. This also applies to all those who have already actively participated. In this way multipliers can be activated again. Even those who participated at the beginning could be invited again at a later date to take a look at the further course of the discussion. A reminder shortly before the end of the participation period can lead to another wave of participation.
Remember: An interested group that stays involved in the process means active community building. With adhocracy+ you can keep your community up to date by writing an info mail (newsletter) to everyone who follows your project.