"The Practice," entering its eighth season Sunday, has injected new cast members James Spader (search) and Rhona Mitra into the mix- while subtracting six stars including Dylan McDermott (search), Lara Flynn Boyle and Kelli Williams.
"The West Wing," meanwhile, will premiere tomorrow without creator Aaron Sorkin (search), who's left the series.
The cosmetic changes will be more visible on "The Practice," with Mitra and, especially, Spader thrown right into the mix on Sunday's season premiere.
"You'll get a storyline involving James Spader's character, Alan Shore, right off the bat - he's thrown headlong into a human-interest case involving a homeless man," "Practice" executive producer Robert Breech told The Post.
"He's not at all comfortable with homeless people and has an awakening in the storyline," Breech said. "It's a wonderful introduction to his character."
Breech said Alan Shore won't supplant the departed Bobby (McDermott) as head of the firm - "He's too independently spirited for that" - and said the characters who left will be alluded to - briefly.
"There's very little time spent dealing with those questions," Breech said. "Rhona's character utters a line that the firm is no longer what it once was, so we're basically reminding people who's gone.
"But we don't spend time explaining where they went," he said.
Breech also said "The Practice" will inject more humor into its storylines this season. "There's more levity, more organic humor, and we'll continue to do cases that are complicated and morally ambiguous," he said.
Tomorrow's "West Wing," meanwhile, will resume last season's cliffhanger in which liberal President Bartlet (Martin Sheen) temporarily left office to deal with his daughter's kidnapping - only to be replaced by right-wing Speaker of the House Glenallen Walken (John Goodman).
That seismic shift in "West Wing" ideology will affect the show's storylines, said executive producer John Wells.
"It's not going to change the character of the Bartlet administration, which has been very socially liberal and fairly aggressive in taking military action," Wells told reporters.
"But you'll see more of [Walken's conservative] views represented on the show. The characters aren't changing - but [Walken's presidency] forces them to . . . hear the other point of view."
Wells also said "West Wing" will downplay Sorkin's habit of writing long, dramatic speeches for his main characters.
"That's a wonderful stage technique that Aaron developed as a playwright and when used effectively it's terrific," Wells said.
"But it's one of the hardest things to do," he said. ". . . Unless we can do it as well [as Sorkin], we'll probably shy away from it."