Maybe she SHOULD do it, but she is not REQUIRED to do it. It is YOUR responsibility to safeguard your important papers in order to protect yourself in cases like this. After she raises the rent, you can take her to small claims court, at which time she has to produce the lease. However, she may choose to substitute all the pages except the one with your signature. In this manner, she can prove, with evidence, that a rise of $500 is allowed in your lease.
Yes, he should give you a new copy, even if he charges you for the inconvenience of having to do it. Hope this helps, good luck.