Before you decide to sell and rebuild your city, I would calculate (with simple excel sheets) how much Hive you spent on your current city.
Then I would calculate how much you could sell your cards for (maybe check last traded prices) and calculate how much hive it would cost to rebuild your new, planned city. If it's cheaper and gets you to earn more SIM, go for it. If it is more expensive and you get less cards, but produce more SIM, then I would calculate a break-even time I'm comfortable with.

Like let's say I lose about 10 Hive when selling and rebuying my city (SIM converted, 800 SIM = 4 Hive).
I would calculate:
If I kept my old city, how much Hive am I currently producing?
If I get my new city that produces more Hive, substract the Hive I would have got from the old city from my new Hive income.
With the difference, the new "extra" Hive, how long does it take to recover the lost 10 Hive?
Then I would've got my break even point from which on I'm better off with my new city than with my old one.

The most important part is to find a new, clearly better layout for the city that is much more efficient.

Generally it is also best to either get low or 0% crime rate if you get building that can get robbed - or only get them if you can get enough so that 1 robbing = 1 day of production.
The worst would be to have 1 bank, 1 shopping mall, 1 casino - each of which can get robbed but they need to procude 1 week worth of SIM to get the robbed money back, so if you get robbed more often they actually lose you money.
So in case of banks it is best to get at least 5 of them - they produce around 150 SIM and in 1 bank robbery you lose 150 SIM, so if you get robbed less than every 2nd day they are profitable.
In case of shopping malls too, maybe only get them if you can get enough of them to produce 75 SIM every day, the amount you would lose in case of a mall robbery every 2nd day.
OFC the other easy solution is to just get crime rate down to 0... or risk losing money and converting your citizens to criminals.