As a Laravel developer, I'd have to say go with Laravel. Although you can move away from PHP, it means any of that legacy code will still need to be completely ported to Java or whatever other language you use. Whereas, staying with PHP, you may find it easier to re-use/adapt that existing code.

Of course, if you're going for a full rewrite, then that might not be a useful consideration. However, even a full rewrite will introduce a lot of changes. When having to do this kind of thing, I recommend changing as few things as possible at once. So staying in the same language while upgrading may keep some pain points down.