Dickov sent on Nathan Tyson late on in search of an equaliser, and the change paid off in injury time as the striker forced the ball home to draw his side level.
The goal ensured that the fans inside the Keepmoat Stadium had something to cheer about, and Dickov said after the game that it was the least his side deserved.
"We were outstanding at times and deserved something from the game," he told the club's official website.
"Lots of credit has to go to the players. We kept going right til the very end and got our reward.
"Preston are a team who will be up there at the end of the season. We did very well to compete with them tonight with our performance."
The draw means that Doncaster are still without a win from their two home games so far this season, but they have won their only league game on the road so far - a 3-0 thumping of Yeovil Town at Huish Park on the opening day.