Migrate an Laravel app to a domain subfolder

I'm gona to migrate a Laravel application from domain

[1] http://example.com

to

[2] https://example.com/app.

Currently on [1] Some clients do a request like 'GET /some'. After host the app on [2] the request is 'GET app/some'.

How do I smoothly make routes to answer as it has been called from [1] so I do not change every route adding the app prefix?

Right now I have to modify all routes (around 50) like this:

Route::get('app/some', function () {
});

I'm using Laravel 5.2 (yes, it is old).

via Chebli Mohamed