1. Have your Spanish tutor ask your questions where you are forced to respond in the subjunctive. (For example, "what would you do if...?" "How did you feel when...?" "Do you doubt that...?")

2. Practicing writing where you are forced to use more complex structures, have a native speaker correct your writing, then review the correction and  practicing writing and reading out loud the correct sentences. 

3. Talk to yourself where you ask yourself and answer questions that require more complex grammar. 

Try a dictation exercise with one of the stories from www.spanishinput.com.

I've found that writing down exactly what you hear is a good exercise for: Grammar, vocabulary, and ear training.