Any time Apple services a part under warranty, you get 90 days of warranty and the balance of whatever warranty was pre-existing. Both of these periods run independently (i.e. you have 5+ months left, so your original warranty end date governs and you don't add + 90 days to your term.)
In the case where hardware serial numbers change or a whole unit is swapped, the warranty transfers day for day and does not get shortened or extended.
Some locations have warranty tolling where you get credit for days where the unit is out of the consumer's hands for repair, but in the case of swap exchanged - that usually is zero days unless they don't have the part and need to order it.
You can look up your exact warranty based on where you bought your iPad from: