Remarketing of your webinar helps reach your target audience, which earlier was a part of your list. It also allows you to create highly targeted and personalized campaigns to gain high attendance for your webinar.
Remarketing helps bring people to your sales pages which were at the conversion stage. It targets leads which remained unconverted. Another way is to approach leads who have already register for the webinar and attended it. It will help convert these leads in to clients.
It is really difficult to get an audience to be a part of your webinar. You always need to look for a topic from your niche that is trending to be able to capture the attention of a large audience. Do some research and look for customer problems. Be relevant and informative with your webinar topic to encourage more people to attend your webinar.