Will I have to do double chin CoolSculpting again after pregnancy if I've done it once already?

The thing to remember is that CoolSculpting results in permanent removal of about 30% of the fat cells in the treated area. But it does not remove all the cells with a single treatment. The amount of fat cells that you have in your body is set by the time you are a teenager. After that point, it more or less depends on how much you inflate them or deflate them. Since you will still have some fat cells left in the area after coolsculpting, it is possible that some of the double chin will reoccur, but, more likely than not, if you gain weight, it will show elsewhere.

coolsculpting and liposuction are permanent, if you gain weight it shoould be elsewhere however some of the fat is still there so there is always potential for the area to get fat still as there are still fat cells there.
if you want a dramatic change necklift/facelift, Implants and fillers will give you that. noninvasive will improve the area and facetite, threads, morpheus, and fillers can be used.  start at home dermarolling to tighten you skin, see emeragecismetics.com where we do free skincare consults daily and recomment MTS roller with anteageMD ampules daily (see dermarolling package).
With significant neck sagging you would need a neck/face lift with muscle tightening (platysmaplasty). at the same time lasers (fraxel,  co2 or erbium) or microneedling RF (fractora, intensif) can be . performed to improve the crepe skin or wrinkles.  You need a formal consultation, as the neck can be treated with a combination approach:
1. micro needling and lasers for texture
2. botox, disport or xeomin to help platysmal bands
3. intensif or fractora RF microneedling for crepe skin and lifting
4. fillers like belotero, restylane silk, juvederm volbella to improve lines and folds
5. neck/face lifting if sagging is prominent or early starting +/- platysmaplasty (muscle tightening)
6. J plasma/Renuvion, thermiRF, inmode facetite for internal tightening
7. ultherapy and thermage for external tightening
8. regular Venus legacy, exilis ultra, or inmode forma treatments with facials to maintain tightness
9. PDO novathreads or silhouette instalift cone threads for lifting and long-term collagen production
see an expert for a full evaluation and treatment plan based on your individual situation and goals.
Best, Dr. Emer