Is my AT trans shot?

[Slicksuby]

I have a 92 n/a L wagon, with about 92,000 miles. I've had no problems with the transmission until today. I was driving on the highway using cruise control and then I noticed that the car was reving a bit abnormal trying to stay at 55mph that I set the cruise at. The car shifts perfectly from stop to about 20 mph then it hessitates to shift into the next gear, but It does eventually, so I can drive about 45 @ a comfortable rpm, thats when it does not shift any higher? Reverse works fine. Ive been searching around, just want to know if my transmission is shot? I put in some leak and slip stop from pep boys. I'm thinking I should drain the fluid and replace it, pray that helps? Any ideas?

[ericem]

Ya definitely replace the fluid now. Are you getting a flashing power light on startup?

[Slicksuby]

No there's no flashing light when I start it up.