if you have LMS 2.5 the upgrade to LMS 2.6 is free of charge;

You just need to install the necessary patches, i.e you need to install the upgrade from LMS 2.5 to 2.5.1 available here:

http://www.cisco.com/cgi-bin/tablebuild.pl/lms25

and then you can go to LMS 2.6:

http://www.cisco.com/cgi-bin/tablebuild.pl/lms26

Additional application patches are availabe for LMS at

http://www.cisco.com/kobayashi/sw-center/cw2000/lan-planner.shtml

Consider to whipe out the databases (reinitialze) and start a fresh discovery afterwards (it depends on the size of your network and the way how devices are propagate into the apps [CM, RME, DFM]). In my opinion, sometimes its quicker then to deale with problems from the previous versions of LMS...