General:
* Go above and beyond
* Put in extra effort
* Exceed expectations
* Do more than is required
* Take the initiative
* Go the distance
* Give it your all
* Make an effort
* Put in the work
* Dedicate yourself
* Strive for excellence
More formal:
* Show exceptional dedication
* Display a high level of commitment
* Demonstrate extraordinary effort
* Be a dedicated and hardworking individual
More informal:
* Go the whole nine yards
* Go all out
* Put in a hundred percent
* Give it your all
The best synonym for "go the extra mile" will depend on the specific context of your writing.