That's a really good question for your orthopedist and physical therapist. I would definitely keep doing your routine used during recovery with hopes you eventually get to the normal point (grade A). Do you feel what the test is showing? Anything like limited range of motion? You just want to be very careful you don't get into a position of reinjuring it if so. I'd wear a knee brace at the very least for now. Here's info on the Lachman test https://www.healthline.com/health/lachman-test#accuracy