Leaving ewes untupped can cause issues with them becoming overfat, getting stuck on their backs, being too fat to conceive next year, etc.
If you have some poorish ground she can run on, or if all your ground is poorish and you can keep her out of any caking you might be doing of the other sheep, then maybe you would manage.
Personally, however, assuming she's in reasonable condition now, I'd spean her lambs either before or as she goes with the tup.
If you flush your ewes as they go to the tup, then you need her dried off before that. So you would need to spean sooner, put her on poor ground for a few days to dry up, then join the other ewes as the tup joins them.
If you don't flush, I'd just spean as you put her with the tup.
If she's in poor condition, and you can't get her into good condition in time, then maybe consider leaving her with the ewe lambs - but be prepared to move her to another group if she gains too much condition
. And plan on getting her clipped early next year, if you can - she'll be ready sooner, having had a year off, and be more likely to get stuck on her back, having a full fleece and a lot of condition.
One other factor is when she will come a-tupping. She may not cycle straight away; if she lambed in May she may not come a-tupping until October or November, even! If you run a tight tupping - take the tup out after 35 days, even sooner - then you may find she's geld in any case