Question: For some reason I feel its overkilling on the use of article(the) here, 

> 
> To refine the results, please use the categories on the left
> 
> 
> 

Can someone help?

Answer: 
In my opinion, the phrases: 

1. 'the results' - refers to the specific results that will be refined;
2. 'the categories', - refers to the specific (provided) categories; and,
3. 'the left' - refers to the specific side (i.e., not the right side, not the top, etc.).

So, I don't think the word 'the' is overused.
As others have said, your sentence is fine, as-is.

However, you might change it to "To refine *your* results, please use the categories on the left."

This would mitigate your concerns with the repeated "the".