Praveen,
Your best approach for upgrade and switching to OpenDJ from OpenLDAP would be utilizing the [export/import scripts](https://gluu.org/docs/ce/3.1.3.1/upgrade/#upgrade-from-30x-to-3131) as this will allow you to install a fresh version of Gluu Server with OpenDJ as your LDAP server and import the old data with the import scripts.