You don't really update 2013, you just download the 2014 installer and install 2014. 2013 will still be on your computer untouched and fully functional as well.
I recommend researching/asking around about whether or not you will want to "migrate your settings" from 2013 to 2014. I've seen many cases where this does more harm than good.
>> how to update to SP1
I guess you speak about AutoCAD 2013, and therefor there is a servicepack 2 available.
Download it from >>>here<<< and then start it (as administrator, with disabled antivirus-software).
- alfred -
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