Once you have some better information, there are a few things you can do to drive attendance:
- Orient the conference around a theme or a topic attendees need to know to do their jobs better, and then ask the key influencers in your industry to talk on that theme or topic.
This is a great way to give people a good reason to attend because you are giving them great value in return for attendance.
- Create an awards night or awards portion of the conference. Get nominations from those in your industry, then announce the awards at the conference--on the stipulation that nominees must attend to win.
- Offer an incentive to attend by knocking 25 or 50 percent off the organization's annual membership fees (if there are fees involved). This would make for an additional reason to turn up for the conference.
- Create an "Elevator Inspector" page on Facebook, or a group on LinkedIn and market back out to people who have that occupational category in their profile.
This can be a quick and effective way to develop a network, and on Facebook you can also advertise to niche groups in a very inexpensive way.
Hope this helps, and even if you have a smaller number of attendees, you can still orient the content of the conference around good, valuable information. That way attendees can start a good word-of-mouth campaign about the value of the conference so you can start prepping now for next year.