Should I Repot, Or Top Up?

[pastafreak]

I have a holly fern, Cyrtomium fortunei, that I bought to keep as a house plant. Towards the end of winter many of its fronds had died back, but there was a bit of new growth. I cut back the old growth. Now, a month on, I can see several dozen new fronds just above the surface...it looks like a mound. Should I pot on to a larger pot, or remove old soil and top up in the same pot?

[spathiphyllum]

I would top up the soil, until it has bounced back, then re-pot if you wish the plant to get bigger.