In version 2.1.2, you can extend the life of the token in the file:
... \ Dreamfactory-2.1.2-1 \ apps \ dreamfactory \ htdocs \ bootstrap \ cache \ config.php
'Jwt' =>
array (
<...>
'Ttl' => 1440 /*60*/
<...>
Changes to other config files (.env) have no effect.