Another possibility is to apply for the new card under the new offer, then consolidate the old card (balance and limit) into it. Citibank will also transfer future charges and credits to the old account number onto the new one.

In this case, you would lose the age of the old card in your credit history, but I don't think the PP card is likely to be among most people's oldest cards (having only been around a few years), so in general that shouldn't be too much of an issue.