Can I ask for a new cheque?

I sublet my room to someone who gave me the last month's cheque at the beginning. I lost that cheque so I ask her to give me a new one. Acknowleging she may not be willing to, I told her that she can give me a new one 6months' later (I consult with the bank they told me if you don't cash the cheque within 6 months the cheque will be ineffective). But the girl still doesn't agree to give me a new one she insisted I have to find the old one in case someone else cash it. (I said it won't because you wrote me name on it and you can't find another one with this foreign name in this small town). We are in Canada by the way. So am I eligible to ask her to give me a new cheque for a month's rent?