How long should I wait before I get my Restylane injections "topped up"?

As long as you have waited well past the initial, expected "post-treatment swelling" period (maybe even up to a month or so), it is fine to add additional volume of the hyaluronic acid fillers if you feel you would like more volume or line correction.

Restylane and Juvederm do wear off faster in the areas with more movement (smile lines faster than under eye tear troughs, for example), so needing to "top off" filler in these areas sooner does make more sense.

There is scientific evidence that over time, the placement of these fillers in the dermis actually does stimulate your own body to build more collagen, so doing a few more injections may also help your body create its own permanent collagen rebuilding which can help your long term outcome even more.

See a board-certified, careful, and artistic dermatologist or plastic surgeon for your treatments.

Injectable fillers like Restylane are essentially a camouflage for the wrinkle, however there is a lot of evidence to suggest it generates natural collagen in your skin and may help support your skin preventing further damage (wrinkling).  There is no doubt that Restylane is a very successful product when used in the smile lines.  More than half of my patients have results that are obvious for greater than 12 months and many have lasted 2 or more years.  Because of the protective effect that I believe Restylane imparts on the skin, I think it is to your advantage to not allow it to fully dissolve prior to a touch-up procedure.  In addition, you will avoid the roller coaster swings by doing smaller amounts more often.