Is attending lectures the best way to study for elec engineering?

From the past I have noticed that my marks have been around high 50s to low 60s. I used to be a mid-high 80s student. University has dropped my grades and I lost all motivation after midterms. I stopped attending lectures. My friend thinks I should attend lectures but I think I should try studying at home. Is attending lectures the best thing to do? I just have 8 days of cles left?