Do I have to melt it all down and get the injections again from the beginning?

I previously received fillers for my under-eyes and chin. Over time, the volume has diminished somewhat, and the shape of my chin feels slightly spread out, so I am writing to inquire about a potential readjustment.

I am wondering if I need to dissolve it all and start over from scratch, or if it is possible to correct it naturally over the existing state with just additional injections or molding. I have heard that the dissolving injections can cause allergic reactions and stretch the skin, so I would prefer not to dissolve it and just apply a layer if possible.

I am also considering lip fillers this time. Since my lip corners tend to droop quite a bit, I am curious about your skill (?) to see if it is possible to design a look where the corners of my mouth appear slightly lifted even when I am not doing anything, rather than an overly artificial shape that looks like a fly has landed on them. I am also curious if there is a significant difference in the duration of the effect between domestic and imported products.