The Baggies are lying in seventh spot in the Premier League after collecting 33 points from the opening 20 matches.
But Foster insists head coach Steve Clarke will make sure there is no easing back even though a top-flight spot for another campaign is already virtually assured.
He said: "The gaffer is very big on not resting on our laurels. I know we've got 33 points and we probably look safe for the season - but that's not what we're aiming to do.
"We're trying to replicate the first half of the season and, if we can do something like that, you never know what can happen.
"We will just keep doing what we're doing. The gaffer is very good at not letting us get carried away or looking at this or that. We will just go about our business and see what's what."
Albion will be looking to make amends for one of their poorest performances of the campaign, a 3-0 defeat at Craven Cottage in September, in a game where Peter Odemwingie was red-carded.
Foster said: "I don't think that result will affect us at all because there were strange circumstances in that game, including the sending-off.
"I just think we played rubbish on that day. We were so bad that 3-0 was a good scoreline for us because they absolutely hammered us.
"But it's a good few months down the line now and we've adjusted a lot more now so they will be coming to our place fearing us much more than we're fearing them."
Albion midfielder George Thorne could be given another start after impressing in the 2-0 defeat against Manchester United at Old Trafford on Saturday.
Thorne was recalled from a loan spell at Peterborough after injuries to Youssouf Mulumbu and Claudio Yacob.
Clarke said: "George was excellent on Saturday. We knew before he went out on loan he was a good player. We'd used him previously in the first team in the Capital One Cup.
"It was a matter of getting him playing time on the pitch.
"He went out to Peterborough, we'd got fantastic reports on him, we knew he was doing well, and I had no doubts he could come in on Saturday and handle the situation."
Thorne said: "I got my chance because of a few injuries and absences and, if I get another chance, I'll have to take it and give the gaffer something to think about.
"Claudio and Youssouf are big misses for us but we can't sit back and think 'what if they were playing?' It's something we have to deal with."
Clarke will check on the fitness of Yacob and Mulumbu (both hamstring) plus defenders Jonas Olsson (groin), Goran Popov (hamstring) and Steven Reid (ankle) before finalising his side.