Increasing demo request through pre recorded webinars

Hello everyone, 

We are running couple of pre recorded webinars through the month, we are using the survey feature to collect demo request but because the survey launch only in the end of the webinar the number of emo request are low, there is no option to use polls during pre recorded and I wonder what our options here? how I increase the number of demo requests by the enegment tools the pltform is offering. Thank you!