Are you saying that you have dimensions that have been pulled to/from CAD Links' linework in the Revit Project and now you want to remove the CAD Links but keep the dimensions?
Hmm...Just spit-balling here, but maybe stripping the CAD down to just those lines being referenced by Revit, saving it under a new name and then using Reload From to replace the original CAD Link with this stripped-down version. Afterwards, select the Link in the Manage Links dialog box, press "Import" button and then press "Ok".
Other than that, I think your Dims are hosed.