Changing Indexed file does not apply

Elastic Stack Elasticsearch
1

Hello!
First of all, I am Elasticsearch newbie. I am currently working on project which was developed by somebody else. I am developing this project on Laravel 4.2, and it uses Elasticsearch. Long story short, currently all search results are sorted by RULE A (file .../Searchers/Books). The rule itself is defined in .../Indexers/BookIndexer.

What is need is to add another RULE B. I added it by the same pattern - defined it in BookIndexer and mentioned right after RULE A.

return [
          'ruleA' => 'desc',
          'ruleB' => 'desc',
        ];

That turned into error with mithril:

mithril.js:2106 Uncaught SyntaxError: Unexpected token < in JSON at position 0

Tried

return [
          'ruleA' => 'desc',
        ];

but with changed RULE A query, and found out that Elasticsearch still indexes by the old RULE A, not the modified RULE A.

As far as I understand, one does not simply change indexes. They need to be reset or something like that?
Of course, I did try googling it. All of the solutions used CURL.
I do not know how Elastic search is usually used, but it me confused and I am not sure what to do.

Any help will be appreciated