Splunk has no built in versioning, nor does it even "make a backup" before overwriting things.
You should set up backups of your Splunk environment. Of greatest importance is capturing your $SPLUNKHOME/etc folder, which includes your configuration information, dashboards, searches, alerts, lookups and things like that. This is as simple as setting up a cron job to, each night, tar up the contents of those directories. If you then save that file onto another system you at least would have recourse to "Ooops I overwrote a lookup I needed".
If you use any number of mechanisms to save a running week's worth of those (renaming them, logrotate, whatever), then suddenly you have at least the core set of information to rebuild your stuff if it goes away.