The 22-year-old joined Spurs from Roma last summer, but he struggled during his first season in England and made just nine appearances in the Premier League.
"I am enjoying my football again," he is quoted as saying by The Mirror. "When I was injured, I was not good, I was not happy. I am happy to be playing football again and helping the team to win.
"This season is a challenge for me because last season did not go as I had hoped with the injuries. But these are things you have to overcome and change yourself. I spent all my holidays over in Argentina with my family and friends. It was great. I now feel 100 per cent, without any injuries.
"You have not seen the best of me yet and you always have to improve. I don't know how far I can go but I will try my hardest to make my team win."
Lamela has made six appearances for Argentina's national side.