This can be caused by numerous things.
Do you have any background sync going on? e.g. Google sync, few email account and so on?
- Don't sync every 5 min, try to increase the sync interval to 30 min e.g.
Do you have a bad signal reception most of the times?
- It can help to change to 2G network if thats the case.
Some other tips:
Try apps like "Greenify". It works even when you are not rooted and can terminate background processes when you don't need them.
The last thing you can do is to perform a factory reset and see if that changes anything. But you'll loose all of your data.
An other option would be to try a second battery and see if that one performs better.
I hope one of these advices can help you a little bit.