英语不要偷懒的句子怎么说

"Don't be lazy with your English" or "Don't take shortcuts with your English" are both ways to express this idea. Here are a few more options:
"Don't let your English skills slip by being lazy"
"Don't neglect your English practice"
"Don't skimp on your English effort"
"Don't slack off when it comes to your English"
"Don't let your English skills go to waste by being lazy"