Try what you had great results with before. Start a bulking diet, get into a routine, and get big. If you did it once, it sounds like you know what you need to do. I'm taking a little time off from doing a 5X5 routine which I loved. I'm going to do a different program for a few weeks, but I still have planned progression. And I'm pretty sure I'll be back on the 5X5 routine in a month or two.

This time don't switch to a lame program. Ask when/if you decide you want to switch programs if you aren't sure.