Configure your cores to use a configset instead.
On a multicore Solr instance, you may find that you want to share configuration between a number of different cores. You can achieve this using named configsets, which are essentially shared configuration directories stored under a configurable configset base directory.
From the reference manual:
If you are using Solr in standalone mode, configsets are created on the filesystem.
To create a configset, add a new directory under the configset base directory. The configset will be identified by the name of this directory. Then into this copy the configuration directory you want to share. The structure should look something like this:
/configset1
/conf
/managed-schema
/solrconfig.xml
/configset2
/conf
/managed-schema
/solrconfig.xml
The default base directory is $SOLR_HOME/configsets
To create a new core using a configset, pass configSet as one of the core properties. For example, if you do this via the CoreAdmin API:
curl http://localhost:8983/admin/cores?action=CREATE&name=mycore&instanceDir=path/to/instance&configSet=configset2
As far as I know there is no way to make an existing core use a config set, so you'll have to back up your configuration and cores, then remove the cores from Solr (do not delete the directories), then readd the cores with the configSet
parameter set to the name of your configset.