Events Organiser – classes folder – widget

I’m a bit confused….

I’ve edited the file in ‘classes’ folder so that at line 171 the template is amended slightly to:

$template = “%event_title% “.__(”,’eventorganiser’).”           %start{{$date}}% – %end{{$date}}%”;

this works great and gives me the result I want and the widget displays as I would like.

However I am aware that whenever the plugin is updated this file may possibly be amended – what should I do to so that this won’t happen?

Thanks in advance for any help