There's no retcon needed.
At the end of Kenobi, the following exchange happens:
Leia: Will I ever see you again?
Kenobi: Maybe. Someday. If you ever need help from a tired, old man. But we must be careful. No one must know, or it could endanger us both.
All that happens in A New Hope is that the adult Leia keeps the implicit promise she made as a child, even thought there's no particular reason for her to do so. It could have been ingrained habit at that point.
There is one bit of the original movie that could be considered retconned due to Kenobi, although it requires absolutely no change in what appears on screen. When Luke announces he's there to rescue Leia and says he's with Obi-wan, Leia reacts with a lot of enthusiasm at the news. Originally, of course, it was that her appeal for help to an acquaintance of her father had been answered. Now, it can be trivially interpreted as her being excited her personal hero had come to rescue her again.
Of course, that requires a reverse bit of retcon later because she doesn't react as intensely to Obi-wan's death as Luke does, however the interpretation there is that by this point she's a somewhat hardened Rebel leader who recognizes that the loss of life is cost that must be paid, as she'd just shortly before witnessed the sacrifice of Rogue One and a large Rebel Alliance task force in order to get her the Death Star plans.
And, of course, her known family and home planet just got blown up in front of her out of pure spite, so one could understand why her reaction to yet another death might be understated.