Bush 1988 was the first consecutive victory since the 1948 Dewey vs. Truman election post-WWII/post FDR.
And that was 5 elections in a row, though FDR won 4 of them.
1932, 1936, 1940, 1944 - 1948
A significant number (not necessarily all) of these things have to happen in a publicly favorable way:
1.) Peace deal with North Korea. Some kind of compromise with Russia in Eastern Europe is a bonus.
2.) Positive trade deal with China. UK & Euro zone deal would be a bonus.
3.) Illegal immigration issue is mostly resolved or heavily diminished
4.) Economy is strong. If there is a recession, it happens after the 2020 election and is fully recovered before 2022.
5.) Current AG finds all sorts of crimes to indict that are Democrats.
6.) Democrats come out of the closet and embrace socialism.
7.) Budget becomes balanced or surplus before 2023.