I have texlive 2016 installed on my windows OS, to use texlive 2017 you need to download it (over then 2.5GO), I think this is a tedious operation every time you want to pass from an old texlive to a recent one.
My question is is there a posibility just to upgrade texlive 2016 to texlive 2017without removing, downloading, and installinig the entire texlive?
You do not have to remove the previous year TeX live installation to install the next one.
Nevertheless, upgrade is not possible. as detailed here, which I invite you to look at, basically it's stated that upgrades could be kind of risky, this is way there is not a supported way to do so and so the "safe way" is to do a fresh install.
Think of the possibility of corruption of the packages if something goes wrong, the hours invested in upgrading scripts and the pain of a possible rollback. The pain is removed, and all of those hours are invested somewhere else in the LaTeX development area.
