The 36-year-old Slipper quit Test rugby earlier this month after his 151st appearance for Australia, making him the third most capped international after Alun Wyn Jones of Wales and New Zealand's Sam Whitelock.
He had been a stalwart of the side right up to his retirement, starting at loosehead prop for eight of the Wallabies' first 10 Tests of the year.
"The guys that have been underneath Slips for a few years, we've learned a lot, but I think no one's going to be able to replace a guy like Slips," Robertson told a press conference on Tuesday as Australia prepared to take on England on Saturday in the first of four November internationals in Europe.
"He's got 151 Tests for his country and almost 200 Super Rugby games. So I think, if you're trying to be something that you're not, I don't think that's the way to go about it.
"We're all good at different attributes, so we're not trying to emulate Slips because we're just not like him. We've got different strengths and weaknesses in our own games.
"I feel that over the last 12 to 18 months we've really built depth in the front row, and we've got some guys that aren't in the squad that are really good props that could easily step into the Wallaby jerseys," added Robertson.
"It's been really exciting to see, but also quite competitive to get that jersey each week."
Robertson, 31, highlighted former All Black Aidan Ross, who made his Australia debut against Japan last Saturday after switching international allegiance, but warned of a difficult time ahead at Twickenham on Saturday.
"I'd say England's front row, and their forwards in general, are one of the best packs, if not the best pack, in the world. We're going to have our work cut out for us.
"Historically England have always had that traditional sort of style of rugby, based around forward play, so we're going to be ready for that and we're looking forward to it," he added.Â
