Rejoice, all you night-time soap opera fans! CBS has made the 1989-90 season worth watching, renewing "Knots Landing," "Dallas" and "Falcon Crest."

The big surprise is that Jane Wyman and Co. will be back for another season. "Falcon Crest" finished 55th in the overall ratings this year and appeared doomed.Apparently, struggling CBS didn't think it could do much better with any new shows.

"Knots Landing" took over the top soap spot from the show that spawned it. finishing 28th. "Dallas" was 30th.

There's still some life in them thar soaps - and we'll get another full season of all the twists and turns, death and deviousness, tragedy and comedy.

-ROUSING FAREWELL: As "Dynasty" limps along in the ratings toward its final farewell, a shocking thing has happened: the show has gotten good again. (And this from someone who hasn't had anything good to say about "Dynasty" in years.)

The return of Sable Colby (of the late "The Colbys") was a masterstroke. She's rotten, and thus great fun to watch.

The departure of Krystal Carrington, now languishing in a coma while Linda Evans takes some time off from the series, didn't hurt at all. Miss Goody-Two Shoes was boring.

After all these years, I can finally accept Emma Samms as Fallon. (She replaced Pamela Sue Martin.) They've made her into a tramp again!

And I'm actually interested in this plot surrounding "the collection" - stolen Nazi art treasures hidden by the Carringtons, Colbys and Dexters.

The credit for the revival has to go to executive supervising producer David Paulsen, hired away from "Dallas." It's unfortunate that all the improvements are for naught. The ratings are dreadful. (The Denver bunch finished 69th this season.)

Of course, "Dynasty" hasn't been pronounced dead yet. It is ABC's highest-rated show on Thursday night. And I thought "Falcon Crest" was done for, too.

-DING, DONG, the witch is dead . . . and now we know how she died.

Knots Landing's resident lunatic, Jill Bennett, was found dead in the trunk of ex-boyfriend Gary Ewing's car several weeks ago. And it looked bad for Gary and his ex-wife, Valene - both of whom had good reasons to kill Jill - for a while.

But thanks to a bit of luck and some nice plotting, it turns out that Jill killed herself! She ingested large quantities of alcohol and drugs, taped her own mouth shut, tied a special knot so she could tie her hands behind her back and used her key to Gary's car to let herself into the trunk - then made the mistake of pulling the trunk closed by sticking her finger into a hole in the trunk, leaving an incriminating fingerprint.

And despite what Mack thinks, I agree with Karen: That witch didn't really mean to commit suicide. (Jill died when she vomited and choked). She just wanted to ruin Gary's life.

But she had it coming to her. Anyone who would try to kill the saintly Valene deserves to die.

-BIG D IN MOSCOW: Well, those Ewing brothers are at it again, only this time they're in Europe.

Bobby and J.R. are trying to steal a deal out from under Weststar and Carter McKay and are in Austria to do it. Then it's on to Moscow, where the Soviets are supposed to turn out to be good guys as the plot progresses.

And aren't you glad that Bobby broke up with Tracy? April is much more interesting.