I think it's something like this (but with the right GlobalInts, and GUI / Label numbers, of course):
(in rep_ex)
string mana;
string exp;
StrFormat (mana, "%d", GetGlobalInt (2));
StrFormat (exp, "%d", GetGlobalInt (3));
SetLabelText (0, 1, mana);
SetLabelText (0, 2, exp);
And make two blank labels on the GUI.