change fluid and filter automatic

[pv-alero]

hi
i have a question, i have a 2.4 Alero with automatic transmission,
my car has only driven 47.500 km (i am living in Europe), this is about 30.000 miles.

The car has never had any problems (except for the front brakes, replaced rotors), but i noticed now the car struggles a little bit between 2.000 rpm and 3000 rpm, it seems he has problems with down shifting, he struggels a little bit and then shifts (i can't better descibe it).

the fluid and filter of the transmission has never changed before (the car has only driven 30.000 miles), but is almost 9,5 years old.
Should i change the the fluid and filter, and what could be the problem of the problem of downshifting (kickdown).