Hey Guys, How do I become Un-Rusty at League Again?

In this season, I've stepped up and gotten this account from Bronze 5 to Silver 1( someone gave me his acc). However, after focusing on school using 90% of my energy, I went back to playing league. In this season, I've stomped the majority of my games and it once had me with a 70% win ratio and 74% win ratio on Vayne. Now, I can't even feel like I used to be a good player