rejaul2005, Have you got the sleep setting set on your player so the LCD turns off when not in use to conserve power. To do this you need to go to Settings>LCD set>Darkle or Black and set the slider to 0 - 30 seconds then press play to accept the setting.
The other thing I have heard but as yet can not verify as I just started testing today is adjusting the battery type in your firmware.
In your firmware there are 3 battery type options
1) 1.5v Alkaline battery
2)1.2v NiH battery
3)3.7v Li-Polymer battery
The claim is if your firmware is set to 3.7v Li-polymer if you change it to 1.5v Alkaline battery it will increase your play time by a couple of hours.
To find out your setting you need to extract your firmware using s1fwx and repair it. Then running the list.bat will open a command window and list all the attributes and files in your dump.bin. Near the top you will find your battery information. If it is at the 3.7v setting you can change it with Firmware Modifier save the setting then reload the firmware back to your player.
s1fwx can be downloaded from
HERE
There is a guide to using it
HERE
Firmware Modifyer
HERE
When I finish testing I will let you know.