I’m suggesting a better replacement for ReloadEvery (https://addons.mozilla.org/en-US/firefox/addon/reloadevery/)
For FF57, migrate to ReloadMatic (https://addons.mozilla.org/en-US/firefox/addon/reloadmatic/).
It seems ReloadEvery already has a recommendation on ExtensionFinder (Tab Auto Refresh), but the latter does not really have anything in common with the original addon as far as the UI goes. ReloadMatic is a much better match as it is very similar to ReloadEvery while at the same time offers additional features.