I recall seeing that it's possible to "bake" or "anneal" or even "remelt" PLA prints to strengthen them. As I understand it, the main effect is improving layer adhesion, which is the main source of weakness in tension in the original Z-axis direction.
Yes, I can print with a hotter nozzle (up to a point) to increase layer adhesion, print with a larger nozzle orifice, print with increased layer height, print slower -- but at a minimum those require reslicing, and affect print appearance (hotter nozzle causes stringing, thicker layers are more visible, etc.).
Baking a print does none of that, as long as it's supported (often done by bedding it in salt).
Question is, how hot? I presume I don't want to go all the way to printing temperature of 180-220 °C, but the plastic transition level of roundly 50 °C isn't hot enough for this.