Qlik Sense Enterprise consists of two parts - Qlik Sense Hub (QSH) and Qlik Management Concole (QMC). If in whole, then QSH is designed to develop and use applications (creating load scripts, worksheets, charts, etc.). QMC is intended primarily for administration of applications and the operating environment Qlik Sense (management of applications, threads, users, licenses, etc.).
For example, your initial load task can be solved as follows:
1. First at QSH you connect to SQL server (see Vladimir answer below)
2. Then at QMC you tune the task of periodically loading data from SQL server by previously created connection.
I am assuming you've created a SQL Server connector while you've developed your application.... This connector is usually created with the creator's Name (see #1 below) so it's recommended that you will make it anonymous (see #2 below) .
You can do it in QMC (which is just a tool to manage your Server environment)...
Just select your connector in the list of available connectors and remove the creator's name from it.
You just need make sure the connector can be accessed by Qlik's Server account (the one is used to reload your data).
It's usually done by default (since the system account has a Security Admin and/or Content Admin roles set for it).
Once you've check all the above, your published app will be loading the data the same way the DEV version does...
P.S. When applicable, please mark this answer Correct or Helpful.