Using KOMAoptions is advised by documentation

thesis/style/studarbeit.sty

-
-% Set page margins. See KOMA Script manual 2.2 for details.
-\typearea[1cm]{2}
-
 \usepackage{lmodern}
 
 \usepackage[german]{babel}

thesis/thesis.tex

@@ -2,6 +2,9 @@
 % switch to scrbook if you want roman page numbers for the front matter
 % however scrbook has no 'abstract' environment!
 
+% binding correction (BCOR) von 1cm für Leimbindung
+\KOMAoptions{BCOR=1cm}
+
 \usepackage[utf8]{inputenc} % encoding of sources
 \usepackage[T1]{fontenc}
 \usepackage{studarbeit}