hmm given that the current version is in fact already 3.6.3 this is somewhat strange.
regardless, in wppizza-preorder.php (root of that plugin)
you will find
define('WPPIZZA_PREORDER_CURRENT_VERSION','<some version number>');
change this to
define('WPPIZZA_PREORDER_CURRENT_VERSION','3.5');
and it should then let you update as normal again
alternatively , you can also just download the latest version from here
https://support.wp-pizza.com/checkout/purchase-history/
if you want to manually update it that way
hope that helps, but let me know if you have further issues of course