You are definitely due for another complete ATF change.
Repair manual states first stop is the ATF condition and level. Check those and report back.
Keep in mind that if you choose to go with a drain/fill, it will only replace what is in the pan, about a third of the fluid. You will want to do at least 2 or 3 drain/fills with some driving in between. That, or get it flushed.
I'd also look into replacing the ATF filter since it's relatively inexpensive and easy to get to. Just a bit messy.