@Joshua Hively (1) Yes, you have to honor the existing leases. (2) Why would a tenant sign a new lease with a "slight rent increase" that has the same move-out date? That's more of a rhetorical question. Best to tell them now that when their lease ends you're going to be rehabbing the units and raising the rent to market rate. If you're lucky they might just move out early! Between now and April starting meticulously planning your rehab. If you think you're going to be spending quite a bit sent up a Pro Extra Account at Home Depot and the equivalent account at Lowes. You'll get some good discounts. And take the time to find yourself a good contractor if you're not planning on doing the work yourself.
If you are keen on getting into the properties to rehab, you could try to offer some money for a mutual release, otherwise you need to honor the lease as written.
DM me if you'd like to discuss options. Congrats on the purchase!