I racked an Octoberfest into my secondary fermenter 2 days ago. I was having trouble keeping the trube out of the siphon, so I ended up with less beer in the carboy than I would like. There's probably an inch between the top of the beer and the "shoulder" of the carboy, where it starts tapering towards the neck. I originally thought it wouldn't be a big deal, since the fermentation would soon force out any oxygen. But, the fermentation seems to have stopped. I haven't seen any bubbles through the airlock, except some caused by disturbing the beer when I move the secondary.
Is it worth adding some boiled water and malt extract to top off the beer, or should I just not worry about it? I haven's used a secondary in the past, so I don't know whether or not to expect much fermentation to happen at this point. It think there are still some fermentables left in the wort. I used the SAF dry lager yeast and I have the carboy in my basement at about 58 degrees F. Should I maybe just try moving the beer upstairs for a day or so, where the temperature is more like 68 degrees?