Do you have to sign papers when renewing an apartment lease?

You are probably on a month-to-month plan. Call your apartment office to be sure.

For a lease to be officially renewed, it has to be signed each time the term is up. If you didn't sign anything when your lease ran out, you can probably move without a penalty. Watch out, though, because if the apartment owner or management company is unhappy that you aren't staying another year, you may not get your deposit back. You should get it back since you aren't under contract to stay, but all kind of bogus reasons are used to keep deposits unjustly.

If no lease is renewed its month to month and either party can give 20 days notice to vaçate. That's law for my state.

You check the laws of the state and the contract you sign. Most states you sign each year ir tem as a new contract, If somehow that doen'tmhappen then there is usually a month to month that kicks in and it is usually quite a bit higher. Some states have a clause that says if you do not inform the lessor of your intentions to move or change the contract the lease goes into effect for another full year.
Read your contract.

i know in ny you sign every time you renew your lease.

Well actually it depends on what your old lease says. SOme say that without signing a new lease then you are on a month to month others (like ours) say that once you pay one month of rent after the lease expired then you have renewed for another year at the same terms (we usually go to the tenants before expiration with a rent increase though so it is moot). You really need to read your lease and see what it says and if it doesn't specify then read up on your state and local laws and see if they say anything about it.

Call them and ask.

You have to sign a new lease yrly.... so if you have not signed a new one then chances are
you are on a month to month...
You are not bound to the old yr lease... but you still are required to give a 30 day notice of quit (move)
that why you will be entitled to any deposit that might be coming back to you...

For all those that said you HAVE to sign a new lease that is NOT true at all. Our lease (we are the landlords) flat out says that if they pay one month of rent and we accept it after their lease end date then the lease is renewed for a year per the same terms. It is written by a lawyer and has been tested in court so I know it is legal in our locale at least. Most leases do state they convert to month to month though, but they do not HAVE to.

Glad to hear the OPs converted to a month to month though.