The Texan has struggled for pace since the championship began, finishing a distant 11th in both Qatar and Spain - races in which his Yamaha stable-mate Jorge Lorenzo finished first and second respectively.
Estoril was at least an improvement, with Spies qualifying fifth and finishing eighth despite admitting to several major mistakes.
The 26-year-old said the performance had been important in rebuilding his confidence after the poor opening, and is aiming to continue the progression this weekend in France.
"I'm looking forward to getting back on the bike again this week," Spies said. "My confidence has been rebuilding well now we've found a good set-up that works so I think we can make another step and improve our performance again at Le Mans.
"It's not my favourite track but I'm going to give it 100 per cent as always to achieve a good result on Sunday."
Team boss Massimo Meregalli said he is confident Spies will be fighting with the front of the pack this weekend in France.
"Last year was not a perfect weekend for Yamaha at Le Mans, a track where traditionally we have been very strong. This year we arrive with a very competitive package so we are confident that we can perform well," Meregalli said.
"Ben has not had an easy start to the year but has been working hard with the team to have a competitive set-up and to rebuild his confidence. I am sure we will see him fighting with the front pack this weekend."
Spies's team-mate Lorenzo, who arrives at Le Mans just one point behind Honda's reigning champion Casey Stoner, said he would have one eye on the championship fight.
"We arrive in good shape having always been in the first two positions in the three races of the year so far, I want to keep this going in Le Mans," the Spaniard said.
"Last year we struggled, especially in acceleration but I feel that this year is going to be a little different. It's a good track for my riding style so we will try to fight for the win again, but [we're] always thinking about the championship."