Keeping Current Members
Many of your members will no doubt be beginners, or at the very least inexperienced at speaking in Esperanto. It will be important that they be given the chance to interact with others in the group. Having experienced speakers can be a valuable asset as they can give talks on a subject. you might need to rein them in, so that the who meeting isn't about them.
While food is usually an incentive for members to come out, eventually you will need something more than food and conversation to maintain attendance. Something like 'Madlibs' in Esperanto might be possible, or other word games. Talking about recent travels or life events is good too. Anything to keep Esperanto 'real' will help maintain the interest level at meetings.