If you had the previous wallet (2.5.1), all you have to do it is to log in with your seed (old seed, it is not necessary to generate a new one) in the new wallet (2.5.2). After that, you have to attach several addresses and your balance will appear in the new wallet.

In my case, some of the coins appeared in my balance after I attached one address. After another five attached addresses, the rest of the coins appeared in my balance.

Cheers!