The Ibrox outfit, thrashed 5-1 by Celtic on Saturday, are 36 points adrift of the champions and nine points behind second-placed Aberdeen.
But Miller believes Celtic have shown just how big an impact some key signings can make.
"You only need to look at them to see the difference a few players make," the 37-year-old striker said.
Despite winning the title last season, Celtic parted company with manager Ronny Deila in the summer and many observers predicted a squad overhaul.
But following the appointment of Brendan Rodgers and the capture of players such as Scott Sinclair and Moussa Dembele, Celtic have made huge strides.
The champions, who remain unbeaten domestically this term and will secure a treble if they beat Aberdeen in the Scottish Cup final in May, have won five and drawn one of the six Old Firm derbies this season, with two of those triumphs finishing 5-1.
Miller hopes his side can emulate their city rivals by making major improvements without wholesale changes.
"There is no doubt we need to strengthen, we need to be better," said Miller, who signed a new deal last week and scored Rangers' goal on Saturday. "But to start thinking you need to sign a whole new team, there is no proof that that is going to be the answer.
"As I said, you only need to look at them to see what a few good signings can make, and existing players being rejuvenated.
"But it is not my job to do that, it is up to the manager and the club to assess where we need to go and how many we need to bring in."
Miller, however, is under no illusions about the scale of the task facing manager Pedro Caixinha and his players as they look to become more competitive next term.
"The manager will assess where he needs to strengthen, that is not for me to say but you just need to look at the league table," he added.
"We seem to get carried away because of where we have been in the past, always used to being up there, being successful, winning trophies and challenging Celtic.
"If Aberdeen had won (on Saturday) they would have gone 12 points clear of us.
"So you need to look at the league table to see how much work is to be done and how much better we need to be next year."
Kenny Miller reckons Rangers can learn from Celtic's example as they look to make major improvements next season.