Well, I think that how you answer this question depends greatly on how you explain the cause of the problems of the Brezhnev era in the first place. I've read a few things about this era and specifically Soviet economic performance in it (some of which contradict each other), and there are various factors at work.
While the USSR's economy, according to its own figures and those of western analysts, continued to grow, it was not growing at the same rates as it had in the past. Part of this could be a sort of diminishing returns - having already established an industrialized welfare state out of an impoverished peasant nation in about 1 generation, the biggest problems were dealt with. But it's also true that the USSR was behind the west in information technology (I have read some material that shows that US intelligence deliberately introduced faulty electronics as imports to the USSR in order to hinder them in this area, but either way the fact was that they didn't have the same capabilities as the west at that time) and in some other scientific fields as well. So a more developed Soviet electronics/computing complex could be one way to push towards a more energetic Soviet economy during this time.
That said, I think the more significant part of "stagnation" was not the economic aspect but the lack of political engagement on the part of the population, and the growing popularity of liberal economic and political ideas among some parts of the intelligentsia. Even if the Soviet economy was doing better, if you end up with a Gorbachev in the driver's seat, that will start a snowball effect of concessions to the west and domestic changes that empower those liberal elements, making a collapse as OTL more likely. Even when it came to the August coup, a majority of party organizations (and if opinion polls from a few years later are to be believed, the population at large) supported the goals of the coup, but more important than numerical majority was political will and engagement.
So for me, the question then becomes how to ensure more political engagement on the part of the Soviet population, something that you would probably have to go back to the 50's or 60's to do. Possibly getting rid of Andropov's health problems might also open a window, but that's a much shorter period of time to work with as far as counterfactuals go.