Hello mellen. I haven't kept gerbils for about 6 or 7 years now, so I'm not 100% sure if advice has changed, but then the advice was definitely not to introduce gerbils that hadn't been bonded from a very young age.
However, I just had a look round and saw that there is some advice out there saying you can introduce, but in very careful circumstances and it doesn't always work. It would be worth signing up for this gerbil forum to pose the question to those who are more up to date and experienced on this. Good luck and sorry to hear of your loss.
We used to have 2 gerbils (both male). One died a few days ago, so the other one is now on his own, which seems really sad. I have read contradictory things about introducing another - would it be safe to do if I bought another young male, should I keep them in separate cages to start with and swap them about so they get used to each others smell? Some things I have read seem to suggest that is it is a young male it might be OK to just put them in together?