Per-profile settings for Java in LibreOffice can be provided by adding a file here: /etc/skel/.config/libreoffice/4/user/config/javasettings_Linux_X86_64.xml

The file should look like this:

<?xml version="1.0" encoding="UTF-8"?>
<java xmlns="http://openoffice.org/2004/java/framework/1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<enabled xsi:nil="true"/>
<userClassPath xsi:nil="true"/>
<vmParameters xsi:nil="true"/>
<jreLocations xsi:nil="true"/>
<javaInfo xsi:nil="false" vendorUpdate="2013-05-02" autoSelect="true">
<vendor>Oracle Corporation</vendor>
<location>file:///usr/lib/jvm/java-7-openjdk-amd64/jre</location>
<version>1.7.0_25</version>
<features>0</features>
<requirements>1</requirements>
<vendorData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vendorData>
</javaInfo>
</java>

When a new user profile is created it will generate this preference file in the user's home directory/.config...