Few months back I asked a question about how to teach my daughter 'L' sound. Now she is able to sound 'La', 'Lu', and 'Lo' properly. But she is still facing the trouble in speaking 'Li', and 'Le' sound.
A possible solution is watching a cartoon or live animal show with her with "LIONS" in it and mention "LION" whenever it comes up on the screen. This is how we taught our autistic son to say certain words that he needed help with. This makes it a fun an enjoyable.