how to make pattern bigger???

[kbh119]

I am wanting to make a dog sweater using this pattern; any suggestions on how to make this bigger?? The dog's chest measurement is 30ins and this pattern only goes up to 24ins.
Appreciate the help
Here's the pattern:


SIZES
To fit dog chest measurement: S (M-L-XL)
10 (13-16-24) ins [25.5 (33-40.5-61) cm].

With larger needles, cast on 41 (47-59-83) sts.
Knit 6 rows (garter st), inc 4 sts evenly across last row. 45 (51-
63-87) sts.
1st row: (WS). Knit.
2nd row: *K1. P1. Rep from * to last st. K1.
Last 2 rows form pat.
Work 1 more row in pat.
Cont in pat, inc 1 st at each end of needle on next and every
row to 51 (61-73-105) sts, then on every following alt row to
55 (69-83-123) sts, taking inc sts into pat. Work 1 row even
in pat.

Leg Openings: Next row: (RS). Pat across 5 (5-7-11) sts.
Cast off 4 (6-6-10) sts. Pat across 37 (47-57-81) sts (including
st on needle after cast off). Cast off 4 (6-6-10) sts. Pat to end
of row.
Note: All Leg sections are worked at the same time using
separate balls of yarn for each section.
Work 1 (1½-1½-2½) ins [2.5 (4-4-6) cm] in pat, ending with
WS row.

Joining row: (RS). Pat across 5 (5-7-11) sts. Cast on 4 (6-
6-10) sts. Pat across 37 (47-57-81) sts. Cast on 4 (6-6-10) sts.
Pat to end of row. 55 (69-83-123) sts.
Cont even in pat until work after neckband measures 5 (6½-
8-11) ins [12.5 (16.5-20.5-28) cm], ending with WS row.
Place marker at each end of last row.
Back shaping: Cast off 6 (7-9-13) sts beg next 2 rows.
43 (55-65-97) sts.
Next row: (RS). ssk. Pat to last 2 sts. K2tog.
Next row: Knit.
Rep last 2 rows to 27 (37-43-67) sts.
Cont even in pat until work after neckband measures
10 (12½-15½-21) ins [25.5 (32-39.5-53.5) cm], ending with
WS row. Leave sts on a spare needle.

Back Edging: (RS). With RS of work facing and circular
needle, pick up and knit 33 (37-51-67) sts along body from
marker to back. K27 (37-43-67) from spare needle dec 1 st
at center. Pick up and knit 33 (37-51-67) sts along opposite
side of body to marker. 92 (110-144-199) sts. Do not join
in rnd. Knit 8 rows (garter st). Cast off. Sew neck and belly
seam.

Leg Edging: (RS). RS of working and double-pointed needles,
pick up and knit 23 (29-32-38) sts around leg opening. Divide
sts on 3 needles. Join in rnd, placing a marker on first st. Cast
off.
Next rnd: Knit.
Next rnd: Purl.
Rep last 2 rnds 3 times more.

[suzeeq]

Easiest way would be to go up a couple needle sizes; if you get 4 sts per inch instead of 5 the largest size should measure about 30-31".