Battery Life on Motorola Cliq

[Cal.Bear.]

I've been using the Motorola Cliq for about 3 months and the battery life fluctuates randomly. I sometimes only have a charge for 10-14 hours while other times I can go 24 hours with heavy use. I updated it and Cell standby uses 43% of battery and Phone Idle uses 38% of battery while display 5%.

I don't know if I should take the phone back and get a replacement or how to improve this.

Thank you for your future advice.