Is it worth it to migrate from laravel 5.0 to laravel 7.0 or better to just rebuild all website? [closed]

I became new junior web developer at the company, senior developer left the company and left all gigantic website in my arms. Code in this laravel project is quite bad and complicated, but a lot of good stuff implemented. I can't decide is it worth it to rebuild everything, or better to try upgrade everything? This project running on laravel 5.0 with php 5. As time is important for me I wonder what do you think guys? Is it worth to invest time to resolve all bugs between packages and so on? It's kind of big distance between laravel 5.0 with php5 on and newest laravel 7 (released today) and php7.

P.S I don't really want to rebuild the site as I am new with SEO stuff, so I am afraid that I can impact quite badly our SEO score after migration to new website.

via Chebli Mohamed