If you do not book online, but via the SEN call center, you should still get the old (current) mileage level.

Already getting the post August 1 for online bookings is obviously considered to be a special promotion by LH, because at least for German based members no mileage level I am aware of is increasing (except, of course, all the upgrades ). I guess they did not think about the increases for NA members when creating this promotion...