Purchase or make your own wood blocks, leg extensions, or risers. Source screws long enough for the task. Turn the table over and pre-drill the center of the table leg and desired extension. Then, follow your predrilled hole with a bit that's larger than the screw head you're using so the screw will be recessed. Use a premium construction adhesive and the long screws to join the pieces together. Stain or paint the extensions to match the legs.