Importing LDAP base DN Error

While doing upgrade in pre-upgrade activity on importing the source ldap only I came to know that my baseDN value is wrong , that is while installing windchillds itself i made mistake by giving baseDN as cn=Windchill12.1,o=XXX instead of o=XXX 

Is there a way now to change the baseDN value and continue on my upgrade ? if so steps for that ?

Thanks in Advance