I've not used Slic3r embedded in Repetier-Host but it looks like it's coming from the End G-Code (Printer Settings --> Custom G-Code --> End G-Code in the standalone version of Slic3r). If you've found that parameter and it's not there, R-H also has a habit of inserting its own start/end g-codes when you run something not off the SD card or when you load something to the SD card with default settings. As I recall I got those out using the Preferences menu.