UPDATE: This is what I got in response to my inquiry over at Themepunch:
Hi,
currently the output of the slider has a height setting of 350px. I assume you forget to change the height of the slider under the slider settings. In case you set it to autoresponsive and set the height to 500px it should have the pleased height.
However it can happen that the themeauthor overwrites these settings by embeding the slider via the prepared options of the theme. In this case please take a look on the php file which creates the page, or contact your theme author to get know where to change this value.
Thanks a lot,
ThemePunch
Does this make sense to anyone? Can you please tell me how to edit the slider with this information?