What type handlebars? Drop bars? Maybe some riser type drops will help you.
These will get you a 15 mm higher position
https://www.specialized.com/us/en/ho...ext=21017-2036
Others make them too. Some more rise, others less. Watch the drop though. Drop varies between bars, so even with more rise for the tops, the drop might wind up not being higher than your current bars.
If that steer tube is steel, and there is a bike frame builder around, they could extend the steerer fairly easy by cutting it off a few cm above the crown and brazing a longer steerer tube on it with an inside union.