I'll toss out some perceptions of how some dances in my area (northeast Georgia) are doing.
I can't absolutely say why some are growing and doing very well versus others that are on life support.

(I apologize if I step on any toes, please chime in and correct me if I'm off. Thanks.)

my dance, Gainesville, Georgia, monthly ... we were very slowly growing to 90 - 120 dancers and then
covid knocked us out. I will be restarting (not as the formal organization, just myself) in April.
I'm pulling back to a small (but loads of character) cabin in the middle of my city
that maxes out at 60 or so dancers. I wouldn't be surprised if I'm flooded with dancers or no one comes. TBD

Sautee, Georgia, monthly ... they've exploded with dancers, a few dances back they had to
turn dancers away because of building restrictions (believe that was around 240 dancers).
I went recently and they had 140 dancers for a local band.
Their overall feel is "family friendly" in that many families come (doesn't mean loads of elementary school
age dancers but not unknown).  That dance I went to had some 20 new
dancers that came from one local college alone (maybe another 20 new dancers from other sources). 
That's not unusual for Sauee. A very wide range of ages attend that dance.
(very old gym, loads of character, middle of nowhere)

Atlanta, Georgia, weekly ... they're stable, 80 to 95 dancers typical. Several new dancers
every week, but overall number doesn't seem to tick up. At the same time, there's not
a lot of anxiety ... stable is okay.  Overall some new dancers stick and some dancers move
away and some dancers age out.

River Falls Lodge, SC, weekly ... very strong turnout, lots (and lots) of young dancers.
(high school, college, and up)
I've heard of so many dancers that it's uncomfortable recently.
This is a quirky, in the middle of nowhere, ancient of days dance hall.
I'm guessing 160 dancers would be tight but maybe doable fit.
    prior younger gen at RFL: https://www.youtube.com/watch?v=BC1THbxnGUQ
    more recent pre-covid lower turnout: https://www.youtube.com/watch?v=S0LVxHb5WvE
    (imagine three times that number of dancers for current RFL dances)

Chattanooga, TN, not sure of frequency ... struggling.

Athens, GA, haven't restarted post covid but heard rumors that they may restart soon.
Pre covid they had a pleasant 60 - 85 person dance in a small community hall in
a park.  Mostly local talent. 

Charlotte, NC, monthly ... restarted last summer, I've heard they're doing great
with a full hall of dancers (130? guessing!).  My pre-covid sense of Charlotte
was they had an unusual demographic with a peak of late 30 to early 40 dancers
along with a reasonable set of younger and older dancers. I'm not used to seeing
a dance with that demographic. Their dance had slacked off some pre-covid but
now is full of energy. I don't know their current demographic.

Asheville's Monday night dance is struggling to find it's footing (recently restarted)
but Asheville's Thursday night dance, OFB, is doing well (just a few data points!).

================

My assumptions are:

Dances with lots of energy to start with and a wide range of ages are pulling in
new dancers and doing well, i.e. keeping a number of them.

Dances without a lot of social event competition, i.e. more rural areas, can (!)
do well.

Here, in the SE, for good or ill, dances that require masks are having more
trouble coming back or getting new dancers than dances that don't require masks.
I'm not making a value judgement in that. Just a note that is likely region specific.

There's, regionally, tension over role terminology, but I don't have
a sense that that is having a strong effect on the number of dancers attending
the above dances.

I realize I'm not directly addressing "getting new dancers to return".
But a growing dance is getting new dancers to return.


Wishing everyone (and every dance) well,
Heitzso
Gainesville, Georgia