I have smile lines that have appeared since kids and weight loss, had filler injected and didn't help. (Photos)

Based on the photos, it appears that the recent weight loss has resulted in mid and lower face volume loss. Your prior injectors were correct in trying to replace the lost volume in the midface using a filler such as Voluma. The problem is you probably  need more filler given the amount of volume you have lost. In cases like yours, a biostimulatory filler such as Sculptra maybe a better option. Sculptra works by stimulating your body to produce its own collagen. 

You don't say how old you are which can determine how much filler you may need overall. From your pictures it may be that you need additional filler in the area.Good options are juvederm vobella or restylane.Other options would be skin resurfacing with a CO2 or erbium laser or microneedling with radiofrequency. We use the AccuPulse by lumenis or the Lutronic Infiniti. Hope this helps.

Thank you for your question. I would recommend consultation with a plastic surgeon who is using Restlane Refyne. This is the newest filler on the market and specifically designed for areas of active motion (such as the smile lines). What is most important about these products is the effect isn't immediate. You need to give two or three weeks for it to settle into place. There have been excellent results, however, for this specific problem you are brining up. Good Luck!