Here are a few ways to make it more interesting:
* Add a description of the coffee: "She spilled a steaming cup of coffee on her jeans."
* Show the reaction: "She gasped, her eyes widening as she spilled a coffee on her jeans."
* Explain the situation: "She fumbled for her phone, accidentally spilling a coffee on her jeans."
* Use a stronger verb: "She splashed a coffee all over her jeans."
Ultimately, the best way to improve the sentence depends on the intended effect and the larger story you are trying to tell.