Wait… I thought the whole topic was due to you losing Ethernet connection… that is hardly 100% up-time 
I have implemented simple error trapping that prevents a quick disconnect/reconnect from crashing my script (see other topic) but I haven’t bothered about auto restarts, etc… not critical in my case as up-time IS 99.9%
If I had a drop in solution, I would have offered it… but I don’t, that is why I made some quick checks and recommended you do the full research … I mean, why would I take my time away from my projects to do it all for you? Had you shown more initiative, I would have as well… but when confronted with nothing but “help mes” and no visible self-effort, I tend to hold back 
Keep searching this site… there are other topics about this…
And I recall similar references about keeping a Blynk server running, or at least restarting it if it shuts down… the principle should be the same for JS Client.