Club captain Forster, who turned 36 last week, has scored five goals in his last four games after recovering from a knee operation.
While Slade is delighted with Forster's hot streak, which included both goals in the Seagulls' first away win of the season at Carlisle, he recognises the club have to monitor the forward's fitness closely.
"We need to learn to manage that," he told The Argus. "He didn't train on Monday and he didn't train last Monday.
"It has got to be done in order that they can perform at their best. It is not easy, because they are getting older and obviously you need to train as well. It's getting the balance right.
"He wants to train and he wants to play - all the good ones do. You think you can go on forever and you can to an extent if you are sensible."