Although I’m sure this has been answered in the last 2 years, I’m going to add an answer just in case people search and find this question - as I did:
There are 2 methods I use.
The first is to use a save game. Save the variables from the player state before you load the new map, and load the save game from an event in the player state. You could even just use Begin Play to load the save game as that will get fired when the new map loads.
The second is to copy the variables to duplicate entries in the Game Instance before moving to the new map, as the Game Instance persists through map loading.
I don’t use the second method very often as it’s cumbersome and leads to similarly named variables across BPs. Also,a save system is something you will likely need to set up elsewhere in the game anyway - so use it for this circumstance as well.