After running a Batch script, a New Apex job gets created. So Whenever I run the batch again, it throws an exception saying:

"The Apex job named "New Job" is already scheduled for execution".

then I delete the existing Apex job from Setup -> Monitoring -> Scheduled jobs to resolve the exception.

I need to delete the existing apex jobs automatically once they are completed.  

Are there any possible workarounds for this? 

Plz help, its urgent