Stretch the mesh. Your goalie stick's mesh should have been stretched prior to stringing, but you can still do it on the stick. Even mesh that was stretched prior to stringing stretch further on a new stick. Forcefully and repeatedly pound a lacrosse ball or your fist into the net where you want the deepest part of your pocket. Regular use of a new stick, particularly catching hard passes and shots or throwing against a wall, will also stretch the mesh.
Loosen the side strings. Untie the knot at the end of each side string and add length where you want the deepest part of your pocket. Keep the mesh within two inches of the sidewall and make sure both sides remaineven. When you've reached the desired depth, retie the knots at the end of each side string.
Loosen the bottom string to add a minimal amount of pocket depth. Simply untie and retie it with more slack. This will only loosen the net at the bottom.
Adjust your shooting strings. Loosening your stick's net will affect not only its pocket depth, but also its release. Make changes to the shooting strings accordingly. Depending on how much depth you added, loosen the bottom string and also add additional strings below it. Create a gradual transition from the pocket of the stick to the release point. Use either nylon shooting strings or hockey laces.