In the wake of the beloved institution (and economic juggernaut) that goes by the name “Frozen,” Disney has decided on a bold course of action: more of the same.

“Frozen II” brings back the gang from the 2013 smash, adds a couple of likable newbies and conjures up a similar batch of Broadway-style songs (composed again by Kristen Anderson-Lopez and Robert Lopez).

The result is a smartly turned piece of family entertainment. It is also redundant, somehow even more than most sequels.

We rejoin Queen Elsa (voiced by Idina Menzel), whose special power is the ability to turn things into ice. She sings well, too.

Her younger sister Anna (Kristen Bell) remains the more down-to-earth family member, and is still being courted by dopey Kristoff (Jonathan Groff). His efforts to propose marriage, inevitably interrupted by circumstances, are a useful running gag.

Actually, Anna and Kristoff keep misunderstanding each other, which leads to the tantalizing possibility that maybe they won’t end up together. “Frozen II” does a lot of that kind of teasing.

Everybody heads into a mysterious forest surrounded by mist. The reason is complicated. The first hint that the film is going to be more convoluted than necessary comes in the opening minutes, when a flashback sketches a puzzling battle between Elsa’s people and a tribe of pagan folk who live in the enchanted forest.

This prologue gives you that terrible sense that we now have to keep track of generation-spanning storylines instead of just sitting back and enjoying the jokes and pretty pictures.

Kristoff’s reindeer is along for the journey, and so of course is Olaf (Josh Gad), the slaphappy snowman. Olaf’s duty in the sequel does not rise to the level of his splendid work in the first “Frozen,” although he and Anna have a fun (and nicely philosophical) duet early on.

Directors Jennifer Lee and Chris Buck, returning from the first film, are especially good at stretching Disney’s visual capacities. Autumnal colors dominate the early section — including a spectacular storm — and one of Elsa’s show-stopping numbers takes her under the sea. It all looks spectacular.

Despite the lung-stretching from Menzel and Bell, the best song sequence is Kristoff’s solo lament, which is rendered in the style of a very bad late-1980s power-ballad music video. Sincere thanks to whatever maniac thought up this idea.

So there’s a lot to enjoy in “Frozen II.” And yet. The first movie had such a brilliant idea (upending Disney’s own tradition of Prince Charmings who save the day), it needed no further elaboration. Finding some new, weaker themes for the sequel removes a little of the luster.

The new film tries on different ideas, maybe too many. Elsa further defines herself, Anna grows (but in ways that are more conventional than the first “Frozen” suggested), and there’s an environmental subtext involving a harmful dam and colonial exploitation.

It’s a lot. “Frozen II” will still haul in a billion dollars, so maybe I should just (so to speak) let it go. But I think the film’s reception might give Disney a lesson in sequel-related diminishing returns.

“Frozen II” (3 stars)

A sequel to the Disney smash, with spectacular visual effects but diminishing returns: What was clear and ingenious about the first movie goes in a lot of different directions here.

Rating: PG, for subject matter

Opening Friday: Alderwood Mall, Cinebarre Mountlake Terrace, Edmonds Theater, Everett Stadium, Galaxy Monroe, Marysville, Stanwood Cinemas, Meridian, Seattle 10, Thornton Place, Woodinville, Blue Fox Drive-In, Cascade Mall, Oak Harbor Plaza