Shrimp overcooks faster than almost any other protein you'll reheat, which is exactly why it turns rubbery so easily. It only needs a minute or two of heat to begin with, so a second round of heat has to be even gentler and shorter than you'd think.
Shrimp is small, lean, and cooks through in a couple of minutes the first time around. That means the window between "warmed through" and "overcooked" is measured in seconds rather than minutes, especially on a second reheat where the shrimp is already fully cooked.
Heat a splash of oil or butter in a skillet over medium heat. Add the shrimp and toss for 60-90 seconds, just until warmed through. Pull it off the heat the moment it's hot, since carryover heat will keep cooking it for a few more seconds even off the stove.
Cover the shrimp loosely and microwave at 50% power in 15-second bursts, checking after each one. This is one of the few cases where checking that often actually matters, since a few extra seconds is the difference between tender and rubbery.
If the shrimp was cooked simply (like a shrimp salad or a lemon-garlic preparation), consider serving it cold or at room temperature instead of reheating it at all. Many shrimp dishes taste just as good, and you skip the rubbery-texture risk entirely.
Cooked shrimp keeps for 3 days in the fridge. It's best reheated only once, since each additional round of heat pushes the texture further toward rubbery.
A dish like pesto shrimp works well with the quick stovetop method, or can simply be served cold since the pesto holds up fine at room temperature.
For general reheating principles across other proteins, see the full meal-prep reheating guide.