The 29-year-old threw 73.93m to win the German championships in Ulm by nearly four metres from her nearest rival, but Heidler knows she has to improve ahead of the world championships.
Heidler, the 2007 world champion, has a season best of 76.48m, behind world leader Oksana Kondrateva of Russia, who threw 77.13m at the end of last month.
The German set the world record of 79.42m in 2011 and having won gold at Osaka 2007, silver at Berlin 2009 and silver again at Daegu 2011, Heidler is bidding for her fourth straight world championship medal.
Meanwhile, 2009 world bronze medallist Ariane Friedrich withdrew from the high-jump at the German championships with a knee injury.
The 29-year-old faces a nervous wait to recover in time to clear the world championships qualification mark of 1.95m, for which she is five centimetres short.
Moscow's Luzhniki Stadium hosts the world championships from August 10th-18th.