[Koha] Koha - Patrons Renewal option

Hi, We have an issue with our Koha installation related to Patrons renewal option. Say I've a patron who has monthly membership effective 10-Jan-2011. If the patron arrives for renewal on 15-Feb-2011 instead of 10-Feb-2011, what happens is the renewal happens from 15-Feb-2011 to 15-Mar-2011. Ideally I want it to happen from 10-Feb-2011 to 10-Mar-2011. There is an option to do this manually right now. Was wondering if there is any better way to handle this. Thanks, Klb Library India.