Two months after undergoing a right knee procedure, the 35-year-old Keane combined well with team mate Gyasi Zardes (two assists) to give the Galaxy plenty of optimism moving forward.
"It feels like at the moment that we're getting people back and then someone is missing through suspension or injury," Keane told reporters after the home victory.
"Come July, hopefully we get everybody back together, everybody fit and healthy, and I think you'll see a stronger, stronger team."
The Galaxy could hardly have looked any stronger early on Sunday as they stormed to a 3-0 lead in the first half.
Keane kicked off the scoring in the 13th minute and added another in the 45th, while Giovani dos Santos tallied in between in a dominant display.
The second half was a tighter affair, however, with Steven Gerrard netting in injury time to complete the scoring after New England, winless in six games, had battled back through Kelyn Rowe and Juan Agudelo goals after the break.
Los Angeles (5-1-3) are now undefeated in seven games and are riding high with their veteran striker back to lead the attack.
"Robbie is very important for us, for the club. He's a great player," Dos Santos said. "I think the chemistry between me and him is getting better every game and for me, it's always a pleasure to play with him."
In the only other match of the day, New York City beat DC United 2-0 after an in-form David Villa scored his seventh goal of the season and Khiry Shelton added another.
