68F seems very high for 34/70. I would normally go for 52-54F until I'm close to FG (7+ days) and then raise to 64-65F for a few days diacetyl rest. Then cold crash. In case I couldn't regulate temperature and only had to keep it steady I would rather keep it at 52-54F for a longer time (3+ weeks). Lager yeasts are not meant to be stressed and fermented that warm, with the exception of if you are able ferment under pressure.
If it's a problem to ferment cold you could try Fermentis Saflager s-23, which could be used to ferment lagers at higher temperature. I've brewed some nice lagers with that one at room temperature.