In the past the approach used by turkeyfox worked for me too. If I went to my desktop and opened my web browser and went to another site, then returned to the game, it would register that I was online. Unfortunately, this hasn't been working with these more recent disconnects. I have to log out of my zoo and then back in, which always takes a while. Rinse, repeat next time it disconnects.
Also, trying to buy animals from franchise trade center is frustrating. I just want a pair of swans, but not only are there almost no females available, when I try to purchase one of the few that is, the server gets and internal error. Looks like the male swan is going to have to be lonely for a while...