How do I update 1.7.2 --> 1.9?

[Homer]

Hallo everyone, I have a simple question.
Right now we a using LetoDMS version 1.7.2.
As the new version 1.9 has some needed features, I would like to update.
But I'm not quite sure how? Just copy all files over the new ones and adjust some settings?
Really that simple? I don't want to risk any data losses as this is a live system not a test system.

Has anyone done this update and can give me some hints what I have to bear in mind?

Thanks in advance

Homer