AUSTIN — Reacting to concerns from Sen. Carlos Uresti and other lawmakers, the Texas Department of Transportation said Wednesday it might extend its moratorium on gravel road conversions in energy-producing regions, and that it will try to provide an additional $250 million for road maintenance and repair.   Uresti, who helped negotiate the initial moratorium agreement with TxDOT in August, applauded the agency for listening to lawmakers and taking positive steps that could limit the need for tearing up paved roads and converting them to gravel in the Eagle Ford Shale and Permian Basin regions. Uresti noted that the 60-day moratorium brokered with TxDOT is almost over, and he urged communities to come to the table with solutions. In the meantime, TxDOT indicated that it would consider extending the moratorium on gravel conversions if more counties stepped forward with alternative solutions. The agency also said, under questioning from Uresti, that no other roads are being considered for conversion to gravel at this time.