My first question would be: do you know why the one bird died? If its death was caused by something contagious, you wouldn't want to bring another bird into your home at this time, of course.
Any other bird that you might bring home, irregardless of where you obtain it, should be kept in quarantine -- away from the remaining bird that you have -- for 30-60 days. Separate cages, obviously. During that time, you'll want to take it to your avian vet for its first well-bird check-up.
You'll have to decide for yourself whether you want to introduce another bird into your home. A single lovebird, as Too said, is usually friendlier than one of a pair. The one that you have will probably adjust quite nicely to being an only child and, right now, just might resent another bird. I would suggest that you put off making the decision for a month or two and see what time brings.