There are many aspects which could cause this change.  In an upright,
hammer weight is a small part so I would not attribute that so much to
the increase.  Spring tension is generally the culprit: the damper lever
springs and the hammer return springs.

Key attitude is a consideration as well.  Are the keys resting at
a steeper incline than before?  The position of the capstan on the
whippen can be affected by this, changing the leverage.  Having the
capstan relocated back towards the flange will require more down
weight.

You wrote, "new hammers, felts, and so on."  That does not give enough
info as to what was done.  Were the hammer butts replaced as well?
Damper felts, levers & springs?  Hammer return springs replaced?

Were the key bushings replaced and are they too snug?  Whether or not
they were replaced, they might need easing, as well as easing the
balance rail hole on the bottom of the key.  Are the flanges repinned
too tightly?   These are friction issues.

Was the touch weight surveyed before replacing the parts?  Many times
it is not the weight which changes so much but the tone.  A softer
hammer will give the impression of needing more input to get the sound
as before with the hard, impacted hammers.

Increasing the lead in the front of the key increases the inertia.
Up weight is lowered as well, this affects repetition.  It's a vicious
cycle.

Regards,

Jon Page, piano technician
Harwich Port, Cape Cod, Mass.