<font face="Arial, Verdana">Slic3r slices it exactly where you place it inside the host, at least if the shape is set correctly. Then it calls Slic3r like this:</font>
<font face="Arial, Verdana">08:45:39.739 : Slic3r command:C:\Program Files\Repetier-Host\Slic3r\slic3r.exe --load "C:\Users\littwin\AppData\Local\RepetierHost\slic3r.ini" --print-center 52,34 --layer-height 0.2 --cooling --fill-pattern honeycomb --solid-fill-pattern rectilinear --fill-density 27.00 -o "C:\Users\littwin\AppData\Local\RepetierHost\composition.gcode" "C:\Users\littwin\AppData\Local\RepetierHost\composition.amf"</font>
where --print-center is the center of the stl object where it should be. Slic3r places loaded object in the center so we need to tell it where we want the center to be.
Are you using the 1.1.7 version bundled or a newer version?