Last year I signed a lease that stated that " the tenancy will be extended ...... for one additional 12 month tenancy at a $1200 rent per month." When the new lease was received there was a $75.00 per month increase. I didn't mind that so much howeever, they now want an additional $75.00 per month for the last month's rent and an additional non refundable pet deposit of $500.00. I paid $500 for this with the original lease and it did not mention that this charge would be recurring. It is mentioned in the new lease with the fee waived for the new lease period. Is this standard practice?

Its not unusual to ask for an additional amount to make the amount of the security deposit equal to one month's rent. Same thing if you were required to pay the last month's rent up front.

But the pet deposit is a bit unusual. However, if its in the lease and you signed the lease...

Is this a management company or private individual?

Has there been damage from the pet?

You are free to not sign anything you don't agree to. Lots of management companies will do stuff like this - I haven't heard of it as much with private individuals. If you've been a good tenant and there's no damage I would certainly try to negotiate with them.

Also, check your state laws (there's a link for each in a "sticky" at the top of this forum.) In many state's it's now illegal to call ANY sort of deposit non-refundable. There may be ways around it - in some cases it may just be semantics (for example I can charge a non-refundable FEE, but not a DEPOSIT.),but it's worth checking into.