Mechanic in a bottle

Have a 96 Civic that doesn’t shift smoothly between 1st and 2nd. This is the second transmission with ~ 100K miles logged. Anyone had any luck with transmission additives that claim some improvement? I know its a stretch but wanted to see opinions if it even worth trying.

Automatic or manual transmission?

What was the problem with the first transmission?

When was the last time the transmission fluid was changed? If never, that would be a good reason.

Civic has 235K miles and I replaced the first automatic transmission at 142K. It was having problems shifting between 1st and 2nd as well. Transmission fluid is changed regularly with the last time at 220K.