Just add weight if it's comfortable to lift. Especially if you just started back you're in the prime to hurt yourself! I know that when I go back I mentally think I can lift just as much as I did when I quit working out (which is never the case).
Just slowly add weight because adding more and more weight is not going to benefit you at all. It's about getting back into shape, not how much you can lift. Take is slow and you'll be fine.
