Lately I have been having major issues with my 95 Mystique's ATX, (Very hard 1-2 shift, going into neutral while going 75

) I ran the codes and on the KOEO 628 came up (Excesive converter clutch slippage.) Ok, would drain/fill the Tranny fluid fix this. (Not flush, I have read enough posts to know that will probably worsen the problem.) I know a tranny replacement is in the near future, but is there any way to prolong the inevinable? Advice, guidence, anything would be greatly apreciated.
Eric