Within reason. A 350V cap working at 250V can be replaced with 450V, no problem. Maybe better reliability, though modern electros are incredibly reliable even at their rated voltage.
There are stories about 450V caps used to bypass 2V cathodes, and failing in months. According to recent literature, that should not happen; maybe it is only true of old production. Still probably a bad idea to go overboard.
This assumes it is just a cap. An electrolytic can act as a Zener and clamp overvoltage. It will start to cook and eventually explode; but apparently this effect has been relied on to protect other parts from short-term overvoltage. It seems like a very dumb idea, especially today when real Zeners and tranzorbs are cheap.