The Baggies have banished their reputation of being a yo-yo club between the top two divisions by guaranteeing a fourth successive campaign of Barclays Premier League football.
But Clarke knows eighth-placed Albion have to continue to look to strengthen ahead of Saturday's encounter with Arsenal at the Hawthorns.
He said: "We have been thinking about next season's plans since September last year. It's something we're always looking and thinking about, how we can improve what we have.
"We would like to think that's going to continue, but if you stand still in the Premier League, other teams come charging past you.
"It's important we don't stand still, it's important we look to improve the squad we have and give the players we've got a bit of help for next season.
"That's something we will endeavour to do between now and the kick-off of next season.
"Whether they are resolved early in the summer transfer window or whether we have to wait until July-August time, only time will tell."
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