Tren isn't a good idea for a second cycle. I would wait until you have done atleast 5 cycles before using tren.
Test + primo would be a very effective and mild second cycle. Primobolan is a great steroid. It is virtually side effect free. It provides a nice cosmetic effect to your cycle, very clean gains and no water retention. You can read up more on primobolan here: What is Primobolan (Methenolone)? - Evolutionary.org
Here's what I recommend:
Weeks 1 - 12
testosterone 500mg/week
primobolan 300mg/week
aromasin 12.5mg every other day