I suspect that you need to register the languagechooserbits variable for the navbar template (I presume when you say file that you mean template).
To do this create a plugin (use something like parse_templates for the hook location) and then put something like the following into the code.
PHP Code:
vB_Template::preRegister('navbar',array(
'languagechooserbits' => $languagechooserbits
));
I've not tested the above but I think that's all you would need. It's just basically allowing for that variable to be used in the navbar template.