Blynk already has connection management options… You need to use whatever 3rd party interface code is reguired to link your devcie with your WiFi/GSM/Ethernet/Telegraph/Smoke signal… followed by Blynk.connect().
Then add in some connection check and logic routines in the void loop() to “disengage” Blynk while keeping the rest of the sketch running when there is no server connection
And finally, periodically attempt to reconnect as desired, instead of constantly every loop cycle.