Spend this time updating your knowledge base via. tech news, tutorial/e-course sites such as Udemy/Pluralsight (if you learn best by video-and-code) or official textual documentation/guides otherwise.
Learn about version control (Git), HTML5/CSS3, ECMAscript 6... PHP and MySQL are still fine. Read guides about modern practices such as mobile-first development, testing via. Chrome developer tools, file minification/concatenation etc. Just learn a little each morning and don't feel overwhelmed!
Consider the points of the following link and don't worry about the "flavour of the week" libraries so much and you'll be fine -> http://programmers.stackexchange.com/a/46760/74224