Depends alot on what you offer/sell but for example, us at
www.nextdoorcash.com have good retention now only due to good members area (targetted) not flooded with plug-ins.
Ad to that the fact that we offer to all our members access to all our other sites. (that we recently added direct marketing with
www.allnextdoor.com 
)
All these factors workout very well when it comes to rebilling
Hope this helps and sorry for the grammar but haven't sleep for +24h.