Read aloud regularly to improve muscle memory.
Use English at work or a volunteer position.
Listen to the radio and "parrot" what you hear.
Watch youtube videos and use your native language to "translate" the correct pronunciation.
Call a customer service hotline to practice.
Listen to music and read lyrics.
Find an American girlfriend.
Listen and repeat with an e-dictionary.
Record yourself and listen to it.
Test yourself with a voice recognition app.
Have you tried any of these?
Do you have any other ideas?