Dafydd Howells replaces fellow Ospreys wing Ashley Evans, Dragons scrum half Luke Crane comes in for Joel Raikes, Elliot Dee starts at hooker and James Benjamin switches from 7 to No 8, Scott Matthews coming in on the flank.
Lewis said: "The changes are all part and parcel of rotating the squad - a tournament like this is not only about winning and improving as a team but about developing individuals, and we will also change things around for our next game, whatever happens against England.
"England are always strong at Under 18 and Under 20 levels, we've looked at some video footage and they are a very big, physical side.
"We lost in the last play of the game against England in last year's tournament, and although neither side will resemble that of last season, we know we can do well tomorrow - if we play as we train.
"We were pleased with the result against Italy, but understandably there were things to work on after that opening game, the line-out and ball retention in particular and we have given those areas a lot of attention since Friday.
"We have some talented players in this group who can add value to the way we play, but we will only do well if every player fulfils his given role within the whole team."
Wales Under 18 v England, FIRA-AER Justin Bridou European Championship semi-final
Madrid, Tuesday 3 April, 3.30pm
H Amos (Dragons); L Hudd (Dragons), S Hughes (Scarlets), J Dixon (Dragons), D Howells (Ospreys); J Maynard (Scarlets), L Crane (Dragons); N Smith (Ospreys), E Dee (Dragons), C Lewis (Blues), J Helps (Scarlets), S Andrews (Dragons), B Roach (capt, Blues), S Matthews (Dragons), J Benjamin (Dragons).
Replacements: E Lewis (Blues), G Rees McPherson (Blues), N Thomas (Ospreys), S Parker (Blues), C Davies (Ospreys), S Clarke (Blues), G Thomson (Blues), B Roberts (Ospreys), A Evans (Ospreys)