I have a cement shower floor and a slab foundation. My current shower floor is tiled and i am currently re-tiling the rest of the shower. i would like to re-tile over the current tile floor but i need to know what to do with the drain. Is there some sort of insert that will give me a new flange and insert into the old one without ripping apart my shower floor?

Thank you for any advice!

First off - It will be better to remove the old floor tile and then install new. This will not only make for a better bond with the tile but will solve your height issue.

However, if you really want to keep the old tile in there then you can raise the drain by a tile thickness. You can make a PVC ring to raise the drain by getting a now drain assembly and cutting off the top 3/8" or so. If the old drain is PVC, then you can chemically weld the two together. If not, then you can use longer screws to go through the new ring and into the old flange.

do not put new tile over old tile
2 reasons, 1st its not right
2nd. the new tile will trap water on top of the old
and doing this will make the old tile cause mold and mildew
it will also make the old grout fail
IF you want a GOOD job
rip out the old tile. and the tile on the wall up 6 or 8 inchs
install a new shower pan and tile over it