The APIs (there are several) for Qlik Sense are quite different compared to QlikView. What you refer to is QlikView specific and not applicable to Qlik Sense.
To get started I would suggest the Developers help site at http://help.qlik.com/sense/2.1/en-us/developer/#Home-developer.htm
I wasn't specific enough.
I've searched this page and foudn this:
What i wanted to do is to reload fresh data in the application from my database
Not sure if you're using .NET, but there's an example in the .NET SDK which is close to what you want to achieve.
Have a look here: Administering Qlik Sense apps using Qlik Sense .NET SDK
If not using .NET you need to use the Engine API and communicate using JSON as described in the API.In that case I suggest that you look into qsock and the other repositories on Github at mindspank/qsocks · GitHub