technology lef file and std cell lef
LEF is technology dependent file. It defines the layer, the metal width, space, pitch and via size. All std cell in lef is designed by that design rule. So you can not immigrate the lef from .25 to .18. Even if the same process with different foundaries.
But if you have technology design rule file. You can manually write the LEF file in technology part (layer, metal and via). For std cell, you can try to previous lef in new project. And then to see if there are some DRC errors.
But in most case, you can not reuse LEF file in new project, except the same technology.