The reforms required would have had much in common with the reforms carried out in the contemporary British Army under the leadership of the Secretary of State for War R.B. Haldane. That is, they would have to have been changes that dealt with pedestrian matters (particularly the machinery of mobilization and supply) as well as the sorts of things, like new weapons, that appealed to readers of illustrated magazines.
Unfortunately for the Russian Army, the situation in the decade that followed its defeat in Manchuria was different from that of its British counterpart. For one thing, any given reform would have had to have taken place on a much larger scale. For another, there was so much more to do.
A simple example of the problems faced by the Russian Army concerns the standard field gun, the 3-inch (76.2mm) Putilov piece adopted in 1902. In many respects, this was a fine piece, comparable to the weapons of its type adopted at this time by other powers. However, because of the state of the Russian steel industry, it was built with substandard metal. As a result, the barrel wore out more quickly than the barrels of its French, German, and British counterparts.
With these difficulties in mind, I think the best thing that the Russian leadership could have done in the years after 1905 was to have reduced the size of the army and used the money saved to invest in the sort of reforms that would have a high payoff in the longer run. These would include such things as investments in industrial infrastructure as well as measures that made a military career more attractive to potential non-commissioned officers.