I would love to help, but you have to help us help you.

What battery are you using? We need to know if it is NiCad, MiMH or LiPo. How many cells and what capacity.
The answer to this should be in the form of (manufacturer) - (chemistry) - (cell count) - (capacity(in mAh))

How heavy is your heli? Weigh it with your battery. If you do not have a scale, take it in to the post office. Our local Office has a scale in the lobby for people to use for letters. It will give us a rough idea of your all up weight (AUW).

Have you considered going LiPo? This is not necessary, but it is a good way to get more power and less weight, two of the issues that often contribute to limited flight capacity like you describe.

There are many more factors that can contribute to the inability to get out of ground effect (OGE). But before we start delving into those, it is best to check the simple ones.

Oh, tell us what charger you are using. Make and Model will help. Is it a peek detect charger, or a wall wart style?

Help us help you. Answer these questions, or ask if there is anything that is not clear.