You don't have to flush all of DCR. Just find the "dead" devices in DCR and delete them. Upgrading to LMS 2.6 with its new device selector may make finding these devices a lot easier. Alternatively, you can export DCR to a file, and hunt it down that way.
If you do find you want to nuke all of DCR, use the following commands:
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl dsn=cmf dmprefix=CMF
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl dsn=rmeng dmprefix=RME
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl
dsn=ani dmprefix=ANI
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl
dsn=dfmItm dmprefix=INV
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl
dsn=dfmEpm dmprefix=EPM
NMSROOT/bin/perl NMSROOT/bin/dbRestoreOrig.pl
dsn=dfmFh dmprefix=FH
Then remove NMSROOT/objects/smarts/local/repos/icf/DFM.rps
(Note: some of these databases may not exist if you do not have the apps installed. Performing these steps will remove ALL devices from ALL applications.)