Hi Sudhanva,
Personally I'm not very clear on what your'e asking. Can you clarify what you mean by: "Reused Test Cases", do you mean Test Cases which are successfully run and completed?
Here below are a list of fields that below to the Test Case which you can query by the WS-API. You can refine your query to specify a condition on these fields that will help you get what you need.
If helpful - great. If still not, then perhaps you can clarify what type of query you're asking for and we can help even more.
Thanks,
Sagi