memory leaks issue

hey hello,
i have completed a game for playbook using marmalade and cocos2dx.
i have allocated 125mb of memory for the game.
everything is working well except when i keep playing the game continuously for an hour or so what happens is my images are getting replaced by a white patch.

but when i close the game completely and start it again then it works fine.

can anybody please help me as in how to solve this issue.
it got rejected in testing and the reason they gave was memory leaks.

are there any tools for keeping track of the memory.
i came to know about metrics but it is lil difficult to understand.

is there any other way to track memory leaks.

any help will be appreciated.

thanks in advance.