Although tiles are an ideal covering for bathroom walls, over the years they will inevitably show signs of wear and tear.  Rather than retiling, there are various techniques you can use to make repairs and improve the appearance of your tiles.

Regrouting
Over time, high moisture levels and general wear and tear can cause the grout in your tile joints to become discolored.  But regrouting can be all that's needed to give your tiles a makeover and get them looking good as new again.

First, you'll need to dig out the old grout, using a grout raker and being careful not to scratch the tiles.  Then get rid of the excess dust by wiping down the surfaces and using a vacuum cleaner to remove the debris from the cracks.  Apply the new grout in the usual way.

Grout Reviver
Using grout reviver is a quicker and simpler alternative to regrouting, although it's a more temporary fix and the results won't last as long as new grout.  To use grout reviver, you'll need to give your tiles a good clean and make sure the surface is totally dry.  Then apply the reviver to all the joints, in much the same way you would if you were painting.  Use a damp sponge to clean off any excess.  As always, follow the manufacturer instructions to achieve the best finish.

Replacing A Broken Tile
Occasionally the odd tile will get accidentally cracked.  If you've still got some leftover tiles from when the bathroom was originally tiled, or you manage to find an exact match, it's possible to replace a broken tile.  Firstly, you'll need to remove the damaged tile.  Wearing goggles to protect your eyes, drill a few holes into the tile to weaken it, using a tile or masonry drill bit.  Take care not to get the drill near the surrounding tiles.  Then use a grout raker to loosen the grout around the edge of the broken tile. 

Remove the tile carefully, using a hammer and chisel.  Then use a scraper to scrape off the old tile adhesive from the wall beneath.  Then apply fresh adhesive and slot in your new tile.  Use spacers at right angles to the tile surface to keep a consistent gap round the edges.  Check that the tile sits flush with the old ones, by holding a batten across the surface.  If necessary, you'll need to adjust the amount of adhesive.  Once the adhesive has been allowed to dry, you can remove the spacers and grout the joints in the usual way.