Reid approached Czech side SK Sigma Olomouc with a view to signing the 23-year-old, but was put off by their cash demands.
Accies always had the option of extending Cerny's deal and were happy to do so, but Reid said making another attempt to sign the talented shot-stopper at the end of next season could be complicated.
He said: "We've agreed to take Tomas Cerny on loan again for another year.
"We tried to make Tomas our player, but Sigma Olomouc were asking for too much money.
"I'm happy with the goalkeeping situation at the club though, because we've also brought in Sean Murdoch, and I'm delighted to get Tomas back.
"I brought him into the side towards the end of the season and he was fantastic, so with him and Sean at the club we're in a very healthy situation.
"Goalkeeper is a difficult position to have tied down and I'm happy with what we've got."