Drupal 7 Bootstrap Subtheme update
The subtheme should inherit all of the basetheme files by default. So in theory you should be able to update the base bootstrap theme and your subtheme will gain all the benefits of those updates (Apart from things you're base theme has overwritten.)

E.g. if in bootstrap you have a page.tpl.php and you also have one in your subtheme then updating the bootstrap page.tpl.php won't have any effect as your subtheme has its own version of page.tpl.php

But anything that hasn't been overwritten/customised by your sub theme should be automatically be picked up by your subtheme. So you don't need to know what version your subtheme is, its effectly whatever the current bootstrap version is your subtheme is a ofshoot of that.