How to improve transmission

[Pontiac Racer]

My tranny has 121xxx miles and it shifts kind of rough past 3.5k rpm from 1st to 2nd. I cant change the fluid now cause its winter and its cold. I think the fluid is good and its red. Are there any ways that i can cheaply try to improve my tranny. I dont want a rebuild or a new tranny

 

[Sven the Sexman]

Lucas Trans Fix...if it won't fix it then it's dying.

 

[nos4blood70]

Shift kit, bottle of Lucas, trans cooler in the Spring.

 

[91parkave]

Sorry but change the fluid and filter. Lucas dosent help a clogged or dirty filter.

 

[Sven the Sexman]

Sorry but change the fluid and filter. Lucas dosent help a clogged or dirty filter.

Clogged/dirty filter would affect all gears...not just 1-2. I tried the fluid/filter on my wife's car for the same issue...then it started throwing lots of codes for excessive shift adapt, threw full line pressure at the trans, and caused rough 2-3, 3-4 shifts. Ended up replacing the trans about 2 weeks later.