I'm assuming you have dried lavender to work with. If this is the case, how about putting some of it in a tea bag and then putting that in your carboy for a few days. That way you can determine when the flavor is right for you, and you won't end up with soap scented apfelwein.
Or, soak the lavender in vodka or everclear for a few days and you'll have an infusion. You can take a sample of wine and add a few drops of this infusion. If it's awesome, put some in the whole batch. If it tastes awful, you just saved the apfelwein from disaster.
As for other wine recipes... I've had some really good lavender lemonade in the past. How about some skeeper pee?