Node type created by custom module doesn't get updated
My wild guess is:

From hook_node_type_insert documentation:


  Respond to node type creation.
  This hook is invoked from node_type_save() after the node type is added to the database.


Because you're not "Uninstalling" the module after you disable it, the content type will be kept, but it will simply be flagged as "Disabled" in the "disabled" column in the {node_type} table.

Therefore that hook is not invoked when you re-enable the module, hence the new fields not added.

So what you need to do is after disabling the module, go to the Uninstall tab and uninstall it, or if you're using drush:

drush dis -y simplegal &amp;&amp; drush pm-uninstall -y simplegal