Additional filings are required to maintain the registration of a trademark. If you do not make these filings your trademark will be considered abandoned by the US Government and all of your federal registration rights will be lost.
Specifically, there are filings due between the fifth and sixth year of ownership, at the tenth year of ownership and every ten years thereafter. The US Government will not notify you of these requirements. It is completely your obligation to make these filings.
If you think an additional filing may be due for your trademark please complete the quote form on this page and a trademark attorney will respond within 24 hours and provide you with a flat rate service quote to handle any filing that may be due.