Reference:
https://docs.splunk.com/Documentation/ES/6.1.0/Admin/ Customizemenubar#Restore_the_default_navigation

The upgraded contents of the staging instance will be migrated back to the deployer and deployed to the search head cluster members. On the staging instance, copy $SPLUNK_HOME/etc/apps to
$SPLUNK_HOME/etc/shcluster/apps on the deployer. 1. On the deployer, remove any deprecated apps or add-ons in $SPLUNK_HOME/etc/shcluster/apps that were removed during the upgrade on staging. Confirm by reviewing the ES upgrade report generated on staging, or by examining the apps moved into
$SPLUNK_HOME/etc/disabled-apps on staging

Reference:
https://docs.splunk.com/Documentation/ITSI/4.4.2/Install/Plan

Either use new app names each time (which could be difficult to manage) or make sure you always include all content (old and new) each time you export.